rg
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Chaotic roads and excessive speed.
Q: What is a number ?
A: That depends. The largest numbers regularly used in calculations
gives some measure of the level of civilisation parhaps. The invention
of logarithms in a dank Scottish castle reveals strange pathways in
man's progress from the caves. We expect chimpanzees to count banananas
and cats to count meal times in the day, but only humans are concerned
with the numerical values for the speed of light.
The range A < x < B for a statistic x is important.
0 Number with no name for most of human history
1,2,3 Numbers worth names and honorific titles.
6 Arrangements of three objects
Small numbers rare diseases, collectors items.
10-99 Tens. Whites facing death penalty in USA.
2^6 64 Number of I-Ching Hexagrams
100-999 Hundreds. Black people facing death penalty in USA.
1000-9999 Thousands. Bosnian men massacred at Srebenica.
10000 Moon (Thai). Brique (French).
100000 Lak (Urdu, Arabic).
Millions people, dollars, animals, diseases.
Jews killed by Nazis. Prison population of USA.
504475641 Surface of earth. km^2
Billions hyperinflation, micro-organisms, science figures.
Telephone numbers
2^32 4294967296. Number of Internet IP addresses.
Arrangements of 13 objects.
Size of PC Hard disk in bytes.
Six Billion World population in October, 1999.
18 Digits 278237540975596768. Surface of Dyson sphere. km^2
20-21 Digits c^2 in metric. Bang for your Gram. Einstein.
Arrangements of 21 objects.
68 digits Shuffles of a standard 52 card pack.
80 digits Protons in Universe. 3/2*136*2^256. Eddington.
> 80 Digits Probabilities, possibilities.
10^10 digits Possibilities for human genome.
Alef-zero Cantor's name for countable infinity.
Here c^2 refers to the square of the speed of light.
Excercise: Try learning the counting numbers from 0 to 10 in a
language which you do not know yet.
Generally you cannot tell how the number is going to be stored in a
computer. Privileged numbers such as Pi or friend's phone numbers are
often remembered by people. Certain other numbers are better not stored
but given generator functions. You don't care whether a right angle is
ninety degrees or Pi/2 radians. Just keep three, four, five and a
triangle.
Euclid described prime numbers, which are numbers with no factors
apart from one and themselves, and irrational numbers which are numbers
which cannot be expressed as fractions. The English mathematian Wallis
is said to have invented a symbol like a figure eight laying on its
side to represent infinity, a number bigger than any ordinary counting
number.
Many numbers used to represent reality on computers are the result
of sampling where a range of values is split into segments and a name
or value is assigned to each segment. Colour displays and images are
the most common example of this.
Fan Dee, Fan Lotteree Thai saying.
Numbers games are another aspect of numbers. 'Running Numbers' has
been dramatized by Hollywood films and folk-rock ballads. These
emphasise a sort of struggle against 'state-control' of numbers.
Buddhist monks in Thailand risk getting killed if they say too much
about the next lottery number. There are cultures where almost everyone
seems to bet on numbers. Next week's imaginary number becomes
yesterday's real number. Just like an alcohol hangover. For many the
lottery number is like the dreams of opium. One could say that Marx got
it wrong and in place of the statement:-
Religion is the Opium of the Masses
Imaginary Number is the Opium of the Masses
Q: What's that special number used in the Theory of Everything ?
A: You mean numbers like 'forty two' which occur in the Hitch
Hiker's Guide to the Universe series. There are many fundamental
equations of physics, starting with Newton's equation for gravitation.
All of these have values expressed in metric units although some
organisations in the Anglo-Saxon world try to cling on to imperial
units of weights and measures. Physical constants are usually given in
'floating point notation': X= M E EXP or M E -EXP where 'M' is a
decimimal number, normally between 1 and 10 and the 'E' stands for a
power of 10, so that 27.5 could be written 2.75 E1 and 1/8 can be
written 1.25 E-1.
A selection of physical constants is given. The first group is taken
from Appendix 2 of 'The Chemical Bond' by Linus Pauling.
Velocity of light c 2.99793 E10 cm/sec
Electronic charge e 4.8029 E-10 statcoulomb
Mass of electron m 9.1083 E-28 gram
Planck's constant h 6.6252 E-27 erg sec
Avagadro's number N 0.60229 E24 /mole
Energy of 1 ev 1.60206 E-12 erg
Wavelength of 1 ev quantum 12397.67 Angstrom
Mass of proton M(p) 1.67239 E-24 gram
Mass of neutron M(n) 1.67470 E-24 gram
Boltzmann's constant k 1.3805 E-16 erg/deg
Gas constant R 1.9872 cal/(deg * mole)
Energy of 1 gram mass 5.6100 E32 ev
Q: What is Algebra ?
A: Algebra is a way of anticipating problems in calculations by
letting symbols stand for unknown numbers. It is said to originate with
the Arabs. There are many Arabic words similar to Algebra. These often
mean force or coercion. The power form is also a name for God.
'Modern Algebra' was invented in the 1800s, and one of the main
advances was the interchange between numbers and functions or
operators. The French mathematicians Fourier and Galois pioneered this
line of thought. Algebra as tought in schools came from much earlier
times. Italy saw the earliest European developments when Cardano and
others came up with a method for solving cubic and quartic equations.
Formal algebra came with the attempts to build mathematics around a
system of axioms in the style of Euclid. David Hilbert and Bertrand
Russell made these attempts fashionable in the early 1900s, but Kurt
Godel showed that this approach had limitations during the 1930s. For
most computer science applications the formal approach is quite good
enough.
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In the 1960s and 1970s the English started to teach 'set' theory in
schools. This was often done in an ideological vacuum. The kids were
not always confronted by such basic questions as race and class in this
context. Nor were they necessarily drilled in hard questions on set
theory which had previously been in the syllabus: calculations about
permutations and combinations. The success of the British National
Lottery shows just how far things have fallen.
Sets are like packs of playing cards, boxes of chess pieces,
selections of lottery numbers, or even populations loving, living and
dying. Early mathematics teaching concentrated on the computational
aspect of set theory, nowadays called Combinatorial Analysis. Horse
races are an excellent example of sets, as are dictionaries.
The maintenance of knowledge about particular sets is of great
economic importance. A goldrush mentality fuels speculation on world
stockmarkets as search engine companies go public. The ignorance of
next week's Lottery Numbers is also important for profits of the
operator. The order of winners in a horse race or the subsets of
football matches with draws or high scores provides the paydirt for a
global money extraction industry.
A set of numbers can be written in brackets: {1 3 5 7 9} is the set
of odd numbers less than ten. A set containing no elements at all is
called the empty set and it is written {}. The set consisting of {0 1}
is special, because 0 and 1 can be made to correspond to values 'true'
and 'false'.
Sets are connected with logic by using the phrase 'a is a member of
A', or 'b belongs to class B'. Such statements are always either true
or false in classical set theory. Fuzzy logic is a new form of set
theory allowing for intermediate values between true and false.
Modern Algebra uses certain conventions such as upper case for sets,
and lower case for members. Many statements of logic can be translated
to theorems in the algebra of sets. The most common are De Morgan's
Laws. A union B or 'A u B' is defined as elements x which are members
of A or B. A ^ B is defined as elements x which are in both A and B.
A-B is the set of x where x is in A but not B. The number of elements
in a set X may be written as c(X). For any set X and subsets A and B
the following identities hold. Here '<=' stands for less than or equal
to. If the intersection of two sets is empty then they are said to be
disjoint.
c(A^B) <= c(A) <= c(A u B) <= c(X)
c(A^B) <= c(B) <= c(A u B) <= c(X)
c(A u B) <= c(A) + c(B)
c(A^B) <= Min(c(A), c(B)) Here Min means minimum.
c(A u B) = c(A) + c(B) - c(A^B) Inclusion and Exclusion
(A u B)^C = (A^C) u (B^C)
(A^B) u C = (A u C)^(B u C)
X - A u B = (X-A) ^ (X-B) De Morgan's Laws
X - A ^ B = (X-A) u (X-B)
If A is a subset of a set X then it is possible to define a post-fix
function called % with A%=100.0*c(A)/c(X) where '/' stands for divide.
The '%' function is merely the ordinary percent calculation.
Exercise:
Q: 60% of housholds have a car and 95% have a TV. How many have
neither ?
A: At most 5%.
Excercise:
Q: 47.5% voted Democrat and 46.7% voted Republican so how many voted
for neither ?
A: At least 18.8%. You can't vote twice, but many did not vote at
all. Divide the population into voters and non-voters. Let U be
the proportion of non-voters. When U is close to 1 then a dictator
selected by popular acclaim could be seen as the most democratic
option.
N=U+(1-U)*0.188 None
R=(1-U)*0.467 Republican
D=(1-U)*0.475 Democrat
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Excercise: Goldbach's conjecture.
Let P={3 5 7 11 13 17 ...} be the set of odd primes and let E={6 8
10 ..} be the set of even numbers greater than four. Then is E=P+P?
Here P+P denotes the set formed by the sums of all pairs p+q with p,q
in P. of P+P. It is already known that E=P+P*P*..P where P*P*P..P is
some product of prime numbers. It is also known that every sufficiently
large odd number is the sum of three odd primes. Vinogradov [1] proved
this in 1937. It is also known, by computer search that any even number
n is the sum of two primes for n < 400,000,000,000,000 (four hundred
trillion in the American style).
Goldbach outlined this conjecture in a letter to Euler in 1742. Now
the publisher FABER is offering a million dollar reward for anyone who
submits a proof of the conjecture, or a counter example before March
15, 2002 [2].
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Mathematicians invented sets long before computer lanuages evolved.
Sets are easy to copy. As a tool of thought, they are unprotected by
legalese or copyright. They are public domain stuff. Mathematical
terminology alone seems a sufficient deterrent. Given two sets A and B
it is possible imagine a table of pairs (a,b). The sets may be people
and cars, or stock market shares and prices. The set of all possible
products is written A x B and a typical element of the set A x B is the
pair (a,b) with a in A and b in B. The set A x B is called the
Cartesian Product. The number of elements of A x B is c(A) times c(B).
If A and B are different horse races, then the prediction of a winner
from each race is called a double, and is simply a member of the
cartesian product. It is also possible to define cartesian products on
more than two sets. The product formula can be generalised. In
particular the size of the cartesian product of k copies of A is c(A)
to the power k.
For any given set X it is possible to define a 'relation' as a
subset R of the cartesian product A x A. An equivalence relation
satisfies three simple rules:
Reflexive If x in X then (x,x) in R.
Symmetric If (x,y) is in R then so is (y,x).
Transitive If (x,y) and (y,z) are in R then so is (x,z).
Given an equivalence relation then it is possible any x in X to
define a unique subset of X containg x: class(x)={y | (x,y) in R}. This
is called the equivalence class of x with respect to R. Any two
equivalence classes are disjoint, for if a in class(x)^class(y) then
(a,x) and (a,y) are both in R, so (x,a) in R by symmetry, and therefore
(x,y) in R and in fact class(x)=class(y). Since the reflexive rule
implies that class(x) contains at least x as an element it follows that
every element of x is in at least one equivalence class. The set of
equivalence classes is often written X/R. Since the classes are
disjoint, and every element is in just one equivalence class we can
write X = union {C(x) with x in X/R}.
Example:
A person cannot exist in a modern state without being slotted into a
cartesian product of some pair of sets. If a person is treated for a
disease the bureaucracy maps that person into the cartesian product of
(people x diseases). A relationship can be defined defined on the set
of people by saying that (a,b) in R if a and b suffer from a given
disease. Not only AIDS, but also multiple injuries will appear in
clusters. Needless to say modern computers are incapable of doing
justice to these types of databases. Analysis of these relationships is
crucial in discussions on public financing.
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Example: Consider education, with the relation R being determined by
school. Two people a,b are in this relation if there is a finite set of
people a=x[0],x[1],x[2], .. x[n]=b where x[i],x[i+1] both went to the
same school. If a person x did not go to school at all, then let (x,x)
in R. Then the population can be broken into a disjoint union of
equivalence classes. When inter-school transfers are common there may
be just a single class. When the education of women is forbidden then
there are at least two classes. In a global world these classes are
unlikely to correspond to geography. A classless society could be seen
as a world where everyone participated in the same distance learning
scheme. Attempts to make everyone participate in the same school
_system_ have been tried many times. When schools have been dominated
by competing religions there have occassionally been problems. Northern
Ireland is seen by many as a classic example. If teaching becomes a
less attractive profession, and the cost of internet connectivity falls
drastically then the uneducated could become replaced by the
'media-educated'. Whoever dominates the media effictively controls
education for large numbers of people.
When a set is finite the class equation can be written:
_
c(X) = \ c(Xi) where X1,X2,.. are the equivalence classes.
/_
Besides relations the subsets of A x B include the graphs of
functions. A function from A to B written f:A->B is simply a subset G
of A x B such that for each a in A there exists a single element b in B
with (a,b) in G. For shares and prices the most common subset of the
cartesian product is the price list, but other functions are possible:
the price in two weeks time, for example, or the previous years low.
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Example: Deoxyribonucleic acid, called DNA, is a molecule made up of
components called adenine (A), cytosine (C), guanine (G) and thymine
(T). Each of these components consists of a ring containing carbon and
nitrogen and part of a sugar like molecule (ribose). As in many organic
compounds the presence of nitrogen gives part of the DNA molecule an
alkaline property, so the components are called bases, as opposed to
acids. The base property helps in the formation of chemical bonds. The
DNA molecule is a chain of any of the bases A,C,G and T in some
particular order. The base pairs A,T and G,C also bond with each other
in a natural way. RNA is similar to DNA except that thymine (T) is
replaced by uracil (U). The AIDS virus is made up of RNA molecules.
There are 16 possible base pairs and 64 triples. Scientists have
determined that certain triples serve to encode amino acids, which are
components of proteins and enzymes. There are about 20-22 amino acids
which occur in the common proteins of life. The 64 base triples may be
divided into equivalence classes according to the particular amino acid
that the base encodes. Such triples are called codons.
There are also some base triples whose function is not explained. It
is conjectured, on very strong evidence, that parts of the human DNA
sequence has been incorporated from orther organisms at earlier stages
of evolution. DNA is important because it is passed from parents to
offspring. Sometimes there are small random changes, but often these do
not matter: the encoding from 64 bases to about 20 amino acids implies
a considerable degree of redundancy. Some very common amino acids will
have more than one codon. The genetic code is a mapping:-
gc: CODONS -> Amino Acids
The mapping is not one to one. Different organisms make the same
proteins for similar functions, but they use slightly different base
sequences. People can estimate a difference between DNA sequences for
making a given protein by counting the different numbers of base pairs.
If A and B are different DNA sequences, then it is possible to define a
distance function d(A,B). For three bits of DNA A B and C the distance
functions satisfy d(A,C) <= d(A,B) + d(B,C). This is the triangle
inequality and it corresponds with our normal notions of space.
DNA space is like normal space with its streets and alleyways.
Species evolution is a set of trajectories in DNA space. A very tiny
part of this story forms the major scenario for Julian Rathbone's
political novel TRAJECTORIES. Einstein used Riemann Geometries to track
real space, and similar tools from analysis and topology will be needed
to explain DNA space.
DNA space is a real battleground. AIDS, TB , Cholera and Malaria
with its associated sickle-cell syndrome are some of the trajectories.
Evolution on computers is usually modelled by some sort of function
iteration and the mathematical discipline of dynamical systems can
provide some of the theory to check out the results. The French
mathematician Poincare invented dynamical systems about one hundred
years ago.
One of the most fascinating scientific ventures of the twentieth
century was the human genome project. Human DNA is estimated to have
about 2.1*10^10 bases. Each DNA molecule may therefore have over
10^10^10 different configurations. Biologists often joke about GOD as
the 'generator of diversity'. Following investment by some private
companies the Human Genome Project is almost finished. In parallel
efforts are being made to elucidate the DNA sequence of
micro-organisms.
This involves intensive number crunching and the employment of
skilled scientists. Biotechnology research is controversial and it has
become easy to mobilise demonstrations against some applications such
as genetically modified foodstuff (GM foods).
The real issue is the expense of the research, its financing and its
public accessibilty. Riemann and Poincare published their results in
academic journals but one hundred years later corporate lawyers are
fighting to prevent the publication of knowledge of the geometry of DNA
space. They are bahaving worse than the wretched priest cults that
tried to monopilise predictions of the Nile flooding in the days of the
pharoahs. The fact is that DNA space is so complicated that they need
the help of the best minds in the world to sort out the navigation
problems.
The corporate elite that seeks to monopolise knowledge of DNA space
are exactly the same types that persecuted Linus Pauling, the first
person to explain protein structure. These business leaders who wish to
monopolise knowledge have allies amongst many conservative religious
people who also want to control access to knowledge.
Just as Newton may have been concerned about stability of the
heavenly bodies, so modern scientists are concerned about other types
of orbits. These are trajectories in DNA space, and also trajectories
in economic space. This last figure is really a consequence of human
demography. Genes and DNA sequences need far more than mere human
populations to express their differences. Micro-organisms have much
larger populations than humans. This is good for evolution, because
certain things must happen with very large populations. Just how the
size of a population may force apparent coincidences is an application
of the specialisation of set theory known a Ramsey Theory. The simplest
statement in Ramsey theory concerns meetings with six people. In such a
meeting there must be either a clique of at least three people who are
mutually acquainted, or else there must be at least three people all of
whom are complete strangers to each other.
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DNA space may seem a very abstract entity, but other people's
failure to understand this could get you locked up in jail for an
indefinate period of time.
The police take DNA samples from the general public following a
particularly brutal and horrific sex murder. They then send the samples
to a laboratory whose corporate owners have a particular financial
interest in incarceration as an industry, just like Stalin's Gulag
system of the 1930s and 1940s. The laboratory is staffed by underpaid
and demoralised workers who use their computers to map areas of DNA
space defined by samples found near the dead body. Tabloid
sensationalism put the police under intense pressure to make an arrest,
so they pick up the person with the nearest DNA match. The victim's
brother, or a parent are a good guess, especially if the victim is in a
minority group. An innocent man is condemned, and those who seek to be
morally outraged look for other people to persecute.
Modern states seek to gain credentials by cataloguing the DNA of
criminal suspects. At least we know that DNA space is a little bit like
Euclidean space.
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As it happens functions got invented well before 'Set Theory'.
Functions are like the act of copying even before the media was there.
Functions were linked with procedures for evaluating numerical
quantities, but methods like table look-up are perfectly good. If you
have a graph G as a subset of A x B and you want to find the value for
x just search the graph G for the correct pair (a,b) with a = x. Call
the corresponding value f(x).
If A,B,C are sets, and f:A->B and g:B->C are functions then it is
possible to define a composition gf:A->C so that gf(x) = g(f(x)). A
function is one-to-one, or injective if f(a)=f(b) only if a=b, and it
is onto, or surjective if every b in B is the image f(a) of some a in
A. A set is finite if c(A) is an ordinary number. In this case it is
possible to define a function from A to the sequence {1,2,..c(A)}. This
comes from any listing the different elements of A as a[1], a[2] ..
a[n] etc. The graph of a function f:A->B can then just be written
b[1],b[2]...b[n] where each b[i] is in B. That is the set of possible
graphs is just the cartesian product of c(A) copies of B.
If there is a function f:A->B which is 1-to-1 and onto then A and B
are said to be in one to one corrspondence. Each b in b must be the
image of a unique a in A with f(a)=b. Define the function g:B->A such
that g(x) is the unique y with f(y)=x. Then g(f(y)=y for any y in A,
and f(g(x))=x by definition of G. The function g is said to be an
inverse of f. A set X is said to be countable if its elements can be
put in 1-to-1 correspondance with the set of counting numbers
{1,2,..n,...}.
The set of positive whole numbers {1,2,3... etc} along with 0 and
the negative numbers is a set. This set is usually noted Z, the symbol
coming from the German word 'Zahlen' for numbers.
Notice that Z has perfectly good 1-to-1 functions that are not onto.
The function n->2*n is 1-to-1 but its image excludes the odd numbers.
Similarly the set of positive numbers {1,2,..} has one to one functions
which are not onto. The obvious choice is the sucessor function n->n+1.
There is a hotel plan named after this fact. The 'Hilbert Hotel' can
accomodate new guests even when all the rooms are full. It is also
possible to double the population even when all the rooms are full. If
a single guest arrives just tell every other guest to move up a room.
If a huge crowd arrives, just tell everyone to move from room number n
to number 2*n. Perhaps not very practical but at the end of the
twentieth century many politicians still seem to think they can expand
prison populations this way. If A and B are two countably infinite
populations then the Hilbert Hotel can also accomodate the set of pairs
A x B, with each pair in a single room. With a finite set of rooms,
double occupancy eventually becomes necessary. This is called the
Dirichlet Box principal. For a hotel of size N with N+1 guests, at
least two must share.
The set of functions from A to B is itself a set. If A has c(A)
members and B has c(B) members then the size of this set, Map(A,B) is
c(B)*c(B)*c(B)...*c(B) multiplied c(A) times. In particular the set of
functions t:A->{0,1} has 2^c(A) elements. This is also the number of
subsets of A. For each X which is a subset of A define the function
tX:Z<-{0,1} where tX(z) = 1 if z is in X and 0 otherwise.
When A is a finite set the set Map(A,A) of all functions f:A->A has
c(A)^c(A) elements. if f:A->A is one to one, then the set sequence of
function values f(a[1], f(a[2]).... f(a[n]) defines f where n=c(A).
There are n ways of selecting b[1]=f(a[1]) but only n-1 choices for
b[2]=f(a[2]) since the function is 1-to-1. Similarly there are only n-2
ways of chosing b[2]=f(a[2]) and so on. The number of such mappings is
n(n-1)(n-2)...2.1 or n factorial. This is often written n!, or
n-shriek. This quantity is also known as the number of permutations of
n objects. If s and t are two mappings of the set N={1,2,3..n} to
itself then it is possible to define the composition of the two
functions r=st by the formula r(i) = s(t{i)) for each i in N. The
permution i:N->N given by i(k) = k for all k is called the identity
permutation. For the set N the number of mappings in Map(N,N) is n^n.
Given any mapping s in Map(N,N) and any k in N the set {k, s(k),
s(s(k), s(s(s(k))), ,.m terms) is a subset of N. When n=C(n) is finite
and m>n then two of the iterated functions (s^j1)(k) and (s^j2)(k) must
be equal. This essentially means that the sequence k[n+1]=s(k[n])
repeats itself after a certain number of terms. This set is called the
orbit of k under the mapping s.
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A set of elements G is a group if the following axioms are true.
G0: For any a,b in G there is a product, ab in G
G1: (ab)c = a(bc) Associative axiom.
G2: There is e in G with ae=ea=a for all a in G.
G3: For any a there exists a' such that aa' = a'a = e
The element e such that ae=ea=a is called the identity element. The
element a', corresponding to a such that a'a=aa'=e is called the
inverse of a.
Example: The set {1} with 1*1=1
Example: Set of shuffles of N cards.
This is a non-commutative group.
Example: Set of subsets of a set with A+B=(AuB)-A^B
An Abelian group satisfies all of the axioms of a group, along with
one further rule.
G4: ab = ba for all a,b in G. Commutative axiom.
In the case of an Abelian group the law of composition is written as
'+', and the identity element is called zero, and given the symbol '0'.
It is said that the Hindus were the first to write about this feature
of ordinary numbers. The additive inverse of an element a is usually
written -a.
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A ring R is an Abelian group, with an additive law of composition
'+', and an additive identity, 0. There is a further law of composition
for pairs of elements r,s in R known as the product. The product of the
elements r and s may be written rs. Rings satisfy the following axioms.
R0: For each r, s in R the product rs is in R.
R1: (rs)t = r(st) Associative axiom
R2: (r+s)t= rt+st and r(t+s)=rt+rs Distributive laws.
Additionally a ring may have further axioms.
R3: There is an element 1 with r1=1r=r for all r in R.
R4: rs=sr Commutative axiom.
Example: The set {0,1}
0+0=1+1=0 1+0=0+1=1; 1*1=1 and 0*1=0*0=1*0=0
This is often called Z2 or GF(2).
Example: The counting numbers 1,2,3 etc along with zero and the
negative numbers -1,-2,-3 etc. form a commutative ring with an identity
element 1 under the usual laws of addition and multiplication.
If R and S are two rings, the cartesian product R x S can be made
into rings by defining componentwise addition and multiplication. The
sum and product of the pairs (r1,s1) and (r2,s2) are (r1+r2,s1+s2) and
(r1*r2, s1*s2) respectively. More generally if X is any set the set of
functions f:X->R can be made into a ring by defining sums and products
elementwise. if f and g are functions in Map(X,R) define (f+g)(x) =
f(x)+g(x) and (f*g)(x) = f(x)*g(x). These definitions create the
necessary ring structure. When R is the ring with two elements the set
Map(X, Z2) is a ring. There is a 1-to-1 correspondance between elements
of this ring and subsets of X. If A is a subset of X then define
(tA)(s)=1 if s in A and 0 otherwise. If A and B are two subsets
((tA)*(tB))(s)=1 if and only if s in A^B and (tA+tB)(s)=1 if and only
if s is in A or B but not both (s in A u B-A^B). This shows that the
set of subsets of a set X may be made into a ring. This is known as the
Boolean Algebra of the set X. Boolean Algebras are important in
Mathematical Logic, and also integrated circuit design.
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In any ring with a 1 then the following identity holds. This is
known as the binomial theorem.
n 2 3 n
(1+x) = 1 + nx + n(n-1)x + n(n-1)(n-2) x + ... +x
------ -----------
2! 3!
k
n! x
Here the general term is --------
k!(n-k)!
n!
The quantity ------- is known as the number of combinations
k!(n-k)!
of k elements taken from n objects. It can be written as C[n,k].
Proof: By induction. Show that if this theorem is true for n, then
it is true n+1, and therefore all n.
1
With n = 1, then (1+x) =1+x.
Given the identity for n consider the expression:
n+1 n 2 3
(1+x) = (1+x)(1+x) = (1+x)(1+C[n,1]x+C[n,2]x +C[n,3]x ....)
k
The coefficient of x is C[n,k]+C[n,k-1]. Writing this in full
C[n,k]+C[n,k-1] = n! n!
------ + --------------
k!(n-k)! (k-1)!(n-k+1)!
= n! k
-------- (1 + -----)
k!(n-k)! n-k+1
= n! n+1 (n+1)!
-------- * ------ = -------- = C[n+1,k]
k!(n-k)! n+1-k k!(n+1-k)
n+1 --- k
So the expression for (1+x) = \ C[n+1,k]x
/
---
and the identity is proved.
To come back to the product of rings, consider the simplest ring Z2,
The Z2xZ2, Z2xZ2xZ2, .. etc form a family of rings. The members of
Z2xZ2 may be written as the set of pairs {(0,0),(0,1),(1,0),(1,1)}.
Alternatively the elements could be written {0,x,y,x+y} with z+z=0 and
z*z=z for all z.
The elements of Z2xZ2xZ2 may similarly be listed as 0, x, y, z, x+y,
x+z, y+z, x+y+z. In terms of co-ordinate listing the quantities x,y,z
stand for triples (1,0,0),(0,1,0),(0,0,1). The sums of any pair of
these elements is a triple with 2 1s. The values x,y,z represent the
vertices of a cube, and the set x+y,y+z,x+z are the next vertices as
you move to the opposite vertex to (0 0 0). The number of points at
distance d from the origin at (0 0 0) correspond to the binomial
coefficients in (1+x)^3. For any number n the product Z2xZ2...xZ2 n
times is exactly like the vertices of a hypercube of n-dimensions. The
points can be represented as n-tuples (0 0 ..1 ..0) etc with 1s in
certain positions less than n. The total number of elements, or vectors
as they are known, is 2^n and there are n with single 1 co-ordinates,
n(n-1)/2 with two non zero coordinates and so on. The general formula
C[n,k] for k non-zero coordinates can be proved by induction similarly
to the binomial theorem above.
n+1 n
Let E=Z2 be the cartesian product of Z2 xZ2. A vector z in E may
be written as an n-tuple x, followed by a or 0 1. The number of such
(n+1)-tuples with k non zero elements are made up from the C[n,k]
n-tuples with the last co-ordinate zero (inductive hypothesis) and
C[n,k-1] consisting of those (n+1)-tuples with k-1 of the first n
co-ordinates being 1 and the last co-ordinate also 1. The formula
C[n+1,k]=C[n,k]+C[n,k-1] gives the reqired proof.
Example:
The British National Lottery.
A winning line is a set of six numbers from the set {1 .. 49}. There
are 2^49 such subsets, but only those with six elements are in a draw.
The six element sets correspond to 49-tuples in Z2 with just six non
zero co-ordinates and there are just C[49 6] of these. This value is
49.49-1...49-5 % 6! or as calculated by this formula
(PRODUCT 49-i6) % PRODUCT 1+i6 = 13983816
The rule of thumb is 14 million to one.
Here PRODUCT X just gives a high precision product of a set of
numbers X. The Index generator 'i' or 'iota' in APL simply gives a set
of consecutive numbers. i6 is the set {0 1 2 3 4 5}. The chance of a
random draw being correct is about 14 million to one, but the payout is
often at much lower odds. The lottery operator accepts unlimited losses
by the public, but the operator shares a single jackpot among the lucky
winners when it loses.
Next | Back|Top|End
The binomial theorem gives a way of counting subsets of sets. It
also holds true in any ring R. When R = Z, the set of integers the
first fiew lines of the triangle look like this.
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
Each number is the sum of those immediately above.
When R=Z2, the field of two elements, you get a triangle with holes
in it. The study of objects with holes in them includes a specialised
field of mathematics called topology. Early topologists included
Hausdorff and Sierpinski. Their major concern at the time was the
search for counter examples in theories of continuous functions. The
early efforts were motivated by the search for space filling curves or
conversely, well behaved 'perfect sets'.
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The set of integers Z is a ring. For any non zero number m it is
possible to define an equivalence relation on Z such that two numbers x
and y are equivalent if and only if the difference x-y is divisible by
m. For any number n > m it is possible to find numbers q and r such
that
n = mq + r with 0
Next | Back|Top|End
Example:
The values of integers are stored in a computer memory. Calculations
are done with a processing unit. Most present day computers do
arithmetic on the set Zm where m is a power of two. Old computers like
the APPLE II had a 6502 processor which only did 8-bit arithmetic. The
numbers 0-255 were divided into the numbers -127 through to 0 then 127.
The value -128, represented as a byte like 10000000 was taken to be
minus infinity. Normal additions and subtractions were carried out
modulo 256.
Apple's technical genius, Wozniak developed sixteen bit arithmetic
by software. He called this sweet sixteen. But even this system has its
limitations. Numbers greater in magnitude than 32000 cause problems.
The computer hardware recognises equivalence classes of numbers, rather
than the numbers themselves. Five kilometers looks like five miles.
NASA programmers found this out the hard way. A recent Mars module got
an excessively hard landing because of this type of mistake.
Next | Back|Top|End
Computers cannot really do accurate arithmetic. Programmers can make
the computer do arithmetic to a high precision, but there will always
be problems which cannot be cracked. All the people that received
erroneous bills or bank statements are fully aware of this fact. If
numbers cannot be dealt with in a satisfactory manner, then why not
just use the computers to sort lists of names and addresses as in 1960s
style sales ledger programs ? If the computer can manipulate text
strings then it should also be possible to implement math systems which
deal with all of the orders of infinity invented by Georg Cantor and
others.
Formal mathematics anticipated these developments in the 1930s.
Church, Godel, Post and Turing contributed very much to the human
achievements of the twentieth century.
Every schoolchild should have opportunity to learn a little about
symbol manipulation systems. The old fashioned business of solving
equations is an excercise in doing this. But solving equations often
makes use of rules which may not be accurately stated. The material
will seem divorced from reality to many. Time to think is important.
An equation for solution involves one or more symbols representing
unknown quantities, usually numbers. If a pupil does not know how to
divide, or possibly to extract square roots, then there seems little
purpose in the excercise. That's where symbolic manipulation comes in.
Next | Back|Top|End
To solve ax=b just write x=b/a. This is an example of a formula.
Perhaps one of the best known recipes of formula is an Indian text
called the Kama Sutra. It's a classical sex manual, and the literal
translation is simply Love Formula. Sutra is comes from the Sanskrit
root word for formula, while Kama corresponds to physical love.
Maxwell's equations are formulae connecting the electromagnetic
forces, and from these come the theory of radio and television and the
ability for people to watch pornographic broadcasts worldwide. The
formula is the connection.
When thinking about formulae forget the calculations for a while and
reach for the heavens.
If R is a ring, it is possible to add symbols to the ring so that
the ring axioms R0 to R4 are satisfied. Just add the symbol X and call
the new ring R[X]. The element X satisfies 1.X=X.1=1 and the value X*X
is written X^2. Multiplying n copies of X is written X^n. The elements
of the ring R[X] are written as sums a[0]+a[1]X+a[2]X^2 etc. with only
a finite number of terms. Addition of two ring elements is done
componentwise, while multiplication is achieved by collecting equal
powers of X.
In the old days algebra was taught in schools by giving the pupils
hundreds of excercises such as:
Multiply 1+2x+5x^5 by 3x^2+2x^3.
Factorise 6x^2+5x+1.
These excercises were often chosen to avoid difficult theoretical
points such as the non-existence of factors. There were often
circumstances where the teachers would not have time to deal with these
difficulties because of political and economic constraints. A media
dominated world will see these difficulties considerably increased for
the next generation of teachers.
Excercise: Verify the following identities.
(1-2a)(9-4a) = 9-22a+8a^2
(3+14t)(14-11t) = 42+163t-154t^2
(12+b)(3-13b) = 36-153b-13b^2
(7c+6t)(2c+3t) = 14c^2+33ct+18t^2
(2-5t)(1-t) = 2-7t+5t^2
(-3c+4t)(-17c^2-13ct+5t^2) = 51c^3-29c^2t-67ct^2+20t^3
(15+14z)(7+5z-z^2) = 105+173z+55z^2-14z^3
(6-13a)(16+a+4a^2) = 96-202a+11a^2-52a^3
(19t-9z)(7t+18z) = 133t^2+279tz-162z^2
(13+4z)(17+19z+16z^2) = 221+315z+284z^2+64z^3
(1+t)(3-5t) = 3-2t-5t^2
(5-16c)(20+c) = 100-315c-16c^2
(7+15c)(5-17c) = 35-44c-255c^2
(9+14y)(3-21y-20y^2) = 27-147y-474y^2-280y^3
(9b+11s)(-15b+7s) = -135b^2-102bs+77s^2
(1+s)(19-6s) = 19+13s-6s^2
(17c+9s)(10c-13s) = 170c^2-131cs-117s^2
(-18c+x)(-13c^2+9cx+2x^2) = 234c^3-175c^2x-27cx^2+2x^3
(7+9y)(2+13y) = 14+109y+117y^2
(7+3s)(18+5s+11s^2) = 126+89s+92s^2+33s^3
(1-11y)(14+13y) = 14-141y-143y^2
(14-17x)(4-3x) = 56-110x+51x^2
(8+17y)(5-6y) = 40+37y-102y^2
(8-5z)(7+17z) = 56+101z-85z^2
(7c+12x)(14c+3x) = 98c^2+189cx+36x^2
(5-9b)(1-b) = 5-14b+9b^2
(11-10b)(1-6b) = 11-76b+60b^2
(18a+13y)(14a+11y) = 252a^2+380ay+143y^2
(8s+15z)(7s-9z) = 56s^2+33sz-135z^2
(-10x+y)(12x^2-4xy+13y^2) = -120x^3+52x^2y-134xy^2+13y^3
(12-7c)(5-11c) = 60-167c+77c^2
(5+9x)(10-7x) = 50+55x-63x^2
(8b-11c)(b+16c) = 8b^2+117bc-176c^2
(3+17z)(20+3z) = 60+349z+51z^2
(2-15y)(19+10y) = 38-265y-150y^2
(5c+18y)(3c+19y) = 15c^2+149cy+342y^2
(7s+t)(s+t) = 7s^2+8st+t^2
(-4b+9z)(-4b+3z) = 16b^2-48bz+27z^2
(-6t+7y)(-2t+y) = 12t^2-20ty+7y^2
(3-z)(1+z) = 3+2z-z^2
(11b+18y)(9b-y) = 99b^2+151by-18y^2
(4b+19x)(6b-x) = 24b^2+110bx-19x^2
(2-a)(14+3a) = 28-8a-3a^2
Some classical formulae attracted great controversy. The first was
the formula for the area of a triangle. If A is the area of a triangle
with sides a,b,c, then the quantities are related by the equation:
A^2 = s(s-a)(s-b)(s-c) where s = (a+b+c)/2.
Effectively the area is given as the square root of a number. This
confounded some ancient philosophers, although the formula is quite
accurate and practical. The formula may be re-arranged to eliminate s.
In the past students and mathematicians would use pencil and paper to
do the calculations, but nowadays it can be done on the computer.
$ AOS"(a+b+c)(a+b-c)(a-b+c)(b+c-a)"
-a^4+2a^2b^2+2a^2c^2-b^4+2b^2c^2-c^4
Giving 16A^2= 2(a^2b^2+a^2c^2+b^2c^2)-(a^4+b^4+c^4)
Systems such as MAPLE, MATHEMATICA, MATLAB , TK-solve and so on can
do most such calculations in an instant, while the user is given time
to think if using the software which should accompany these notes.
Whatever the reader may think of the calculations, the symmetry of the
formula should be quite evident. The values a,b,c represent the lengths
of sides, or distances in space. When a=b=c it is easy to see that
16A^2=3a^4 or A= #sqrt(3/2)a^2 , where #sqrt stands for square root.
In fact the formula as written looks valid for all sets of numbers.
However if a,b,c represent the lengths of a normal triangle then we
know that a<=b+c and the same for the other sides. This is certainly
true in Euclidean space, and also DNA space.
Two of the most famous formulae in history are:-
(1) Pythagoras Theorem: a^2=b^2+c^2 for right angled triangles.
(2) Einstein's energy equation: E=mc^2.
Next | Back|Top|End
Pythagoras Theorem is easy to prove by algebra. Given a right angled
triangle with sides of length a,b,c with a<=b<=c construct a square of
size a+b, and fit in four triangles and a square as shown below.
...b............................
. .. . . Area of Square = (a+b)(a+b)
. . . . b Also the area is the sum of
. . ......c. . four right angled triangles
a . ........ . and the center square of side c.
. . .... Now the area of a right angled
. c . . triangle is given by
. . . . Area = base x height/2.
. . . .
. . . a Large square = a^2 + 2ab + b^2
.. c . = c^2 + 4(ab)/2
. . ... . . = c^2 + 2ab
. ....c . .
b ..... . . So a^2+2ab+b^2= c^2 + 2ab
. ..... . . a^2 + b^2 = c^2
.......a...................b....
This proof is reputed to have originated in China.
The Triangle formula is a consequence of Pythagoras Theorem.
+----------------------------------------------------------+
| |
| A. |
| ... .. |
| . . .. |
| . . .. |
| .. . ... |
| c. . .. b |
| . .y .. |
| .. . ... |
| . . .. |
| . . .. |
| .. x . a-x .. |
| B..............X........................C |
| a |
| |
+----------------------------------------------------------+
The triangle ABC may be split by drawing a perpendicular line from
A to its opposite side. If the numbers a,b,c represent the lengths of
the sides and x,y the distances BX and AX then we have :
Area = A = 1/2 * base * height = ay/2
Pythagoras theorem can be applied to the triangles ABX and
ACX giving equations for x and y.
c^2 = x^2+y^2 (1)
b^2=(a-x)^2+y^2 (2)
It is possible to compute y in terms of a,b, and c.
Subtract (2) from (1) giving
c^2-b^2=-a^2+2ax or 2ax = a^2+c^2-b^2
For the area A the equation can be written
4A^2 = a^2y^2 = a^2(c^2-x^2)
= a^2(c^2-((a^2+c^2-b^2)/2a)^2)
16A^2 = (2ac)^2 - (a^2+c^2-b^2)^2
= (2ac+a^2+c^2-b^2)(2ac-a^2+b^2+c^2)
=((a+c)^2-b^2)(b^2-(a-c)^2)
=(a+b+c)(a-b+c)(b+c-a)(a+b-c)
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In May 2000 a Phillipino hacker released the Love Bug virus. More
exactly the offending code was a 'Visual Basic Worm'. The worm was
easily able to propogate amongst the computers of governments and large
corporations. Following attacks on capitalism by demonstrators in
Seattle, Washington, London and Chieng Mai governments and lawmakers
became unduly sensitive and concentrate more forces on tracking school
kids than they ever put into catching Osama Bin Laden.
The Lovebug worm is a script written in Visual Basic which is
activated when users of Microsoft Outlook open e-mail attachments. An
e-mail attachment is an encoded package that comes along with a plain
text message. There has never been any guarantee that e-mail
attachments are wholesome. Indeed many in large organisations will
exchange pornographic images and suchlike. It is rumoured that the
Lovebug Worm cost it's victims up to one billion dollars in lost
business. The world probably benefitted because much of this so called
'business' is leading to environmental degredation and oppression of
the poor. The writer, Ramel Ramirez did the world a favour.
The ease of propogation of the worm highlights the incredible
stupidity of corporate fascism. The genetic sequencers promise cure for
malaria or AIDS by their understanding of DNA but the industrial
complex is unlikely to deliver such results quickly. What they are
really seeking is loads of money immediately, and the benefits to
humanity will 'trickle down' towards the poor.
Modern medicine has made vast advances in explaining immunity, but
the explanations offer little consolation to individuals. What happens
is that immunity works in whole populations [4]. Those who are immune
to a disease act as a barrier to the propogation of the disease causing
pathogen. In fact only a relatively small proportion of the population
need immunity to drastically curtail disease propogation. This effect
is called 'herd immunity'. Herd immunity was important in preventing
the Love Bug worm doing any real harm. Users of computers whose
managers were not addicted to Microsoft Office and it's cancerous
overgrowths were completely unaffected.
These ideas about immunity come from physics. Boltzmann and Maxwell
contributed to the kinetic theory of gases which describes the
movements of gas molecules as random walks with very predictable
effects for the extremely large numbers of molecules involved. This
random motion of molecules can also be observed with a microscope, and
is named Brownian motion after the discoverer. Temperature is related
to the velocity of motion of molecules.
Mathematicians had been working on solutions of the heat equation
since the 1820s. This equation and its solutions arise in areas of
research ranging from the Theta Functions of Jacobi to Wall Street
derivatives market.
Following the success of the kinetic theory of gases the same sorts
of calculations were applied to newly discovered particles such as
protons and neutrons. These calculations were particularly important in
predicting the chain reactions involved in nuclear fission. Neutron
absorbers and reflectors became key components in nuclear detonators.
The same models are applied to population dynamics. The modern
interest in ecology and species diversity shows that people can be
mobilised to express forceful views on possible absorbing and
reflecting barriers in DNA space, but many of the most powerful players
are sadly deficient in presentation skills. They also leave their own
computer systems vulnerable to attack.
Random walk explanations start from very simple models. The first
model is the simple coin tossing game with sequences of heads or tails.
A sequence THHTH.... etc can be translated into motion in many
different ways, but the simplest is simply counting the number of
occurences of one of the faces, which is considered a success. This
gives an ever increasing sequence, which can be translated into the
motion of a point just moving forever in one direction at an irregular
velocity.
It is possible to ask the probability that the point has moved k
steps in n trials, and also where the point is most likely to be. With
one trial then there is either no motion, or a displacement of one
step. With probabilities of success and failure given the values p and
q the number of successes S is 1 with probability p and 0 with
probability q. This can be written pX+q where X is symbol. When p=q=1/2
then just write 1+X. It then happens that all the probabilities of
moving k steps in n trials can be obtained by reading of the
coefficients in the series (1+X)^n, dividing by a factor of 2^n. There
are many proofs of this in textbooks, but the idea is to reduce
statements about motion to features of polynomial multiplication.
Polynomials that correspond to movement or growth are often called
generating functions. What physicists did was to go and take straight
limits giving things like the bell curve much loved by certain
statisticians and social scientists.
Whatever the nature of the proof the theory works well in practice.
Any player of backgammon or monopoly will be aware that seven is the
most common total of two dice. The relative probabilities of the totals
are given by reading off the coefficients of
(x+x^2+x^3+x^4+x^5+x^6)(x+x^2+x^3+x^4+x^5+x^6)
x^2+2x^3+3x^4+4x^5+5x^6+6x^7+5x^8+4x^9+3x^10+2x^11+x^12
This gives seven as the most common outcome. Other features of
generating functions are their ease of application. The rules don't
change across different computer or language systems. As it happens
genetics follows the same patterns. Going from one generation to the
next various outcomes can be read off as coefficients in a polynomial.
Many scientific processes are explained by taking limits of these
coefficients, but DNA space is different. Just like physics has string
theories, so undoubtedly we will see non-archimedian metrics applied to
DNA space.
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In the game of Bridge each player gets 13 cards from a pack of 52.
Decisions are made on point counts for high cards. The most frequently
used system counts 4 for an Ace, 3 for a King, 2 for a Queen and 1 for
a Jack. Zia Mahmood publicised a generating function for this point
count in The Guardian.
(1+y)^36 (1+xy)^4 (1+x^2y)^4 (1+x^3y)^4 (1+x^4y)^4
Zia posed a question about these distributions in his Christmas
competition which is published every year in the Guardian. He got
several exhaustive analyses in his responses along with correct answers
on bidding and playing hands. The formula was sent by Dr Jeremy Bygott
of Oxford. The coefficient of y^13 gives the generating function for
point count in a 13 card hand. This is a beautiful solution.
Next | Back|Top|End
Q: What is an array ?
Medieval times: Lords of the Array.
An array is a set of numbers arranged in lines, often called rows or
columns. This meaning of the word is relatively new.
In feudal times the King could call on his vassals to provide arms
and men in times of war. The managers of these mixtures of unwilling
conscripts along with vain and boastful knights were called 'Lords of
the Array'. The Chinese lost Hong Kong and Shanghai because they
adhered to this system well into the nineteenth century. The British
themselves fell victim of these feudal hangovers when a coterie of
upper class generals, collectively termed 'The Donkeys' went and
ordered hundreds of thousands of working class men to charge German
machine gun emplacements during the First World War. These generals had
learned nothing from the losses of the Chinese during the Opium wars of
the 1840s and 1850s.
In the 1700s Euler investigated the problem of '36 army officers'.
There are six ranks of officer, and six regiments. The idea was to
arrange these officers in a 6x6 square so there were no two from either
the same rank or regiment standing in line.
In 1782 Euler conjectured the problem was impossible.
In 1900 G.Tarrey showed that Euler had been right through a brute
force enumeration of all 6x6 latin squares.
Godement's treatise on Algebra, written in the 1960s contained
tables showing the number of bombs dropped by the Americans on
Viet-Nam. An excercise asked the reader to verify the associative laws
of addition by adding up items in these tables.
More recently Ian Stewart described a military array problem in his
regular Scientific American column [3]. The commander in chief (C-in-C)
inspects his troops arranged into a certain number of squares. The
C-in-C then takes his place in the army whose order of battle is a
single huge phalanx, which also happens to be a square. They are
unlikely to win the battle this way, but the size of the army is what
counts here. The C-in-C inspects 61 equal squares of troops. The size
of the army is the lowest integer solution to Y^2 = 1+61*X^2.
The equation Y^2-M*X^2=1 is known as Pell's equation. It is a
perennial favourite for maths puzzles.
Excercise: Try the problem with 61 squares, then say ... 9349.
Excercise: For the table top.
You can arrange 84 match sticks to make a 6x6 square or a set
of 28 triangles as shown. Try and make larger such arrangements.
-- -- -- -- -- -- /\
| | | | | | | --
-- -- -- -- -- -- /\/\
| | | | | | | ----
-- -- -- -- -- -- /\/\/\
| | | | | | | ------
-- -- -- -- -- -- /\/\/\/\
| | | | | | | --------
-- -- -- -- -- -- /\/\/\/\/\
| | | | | | | ----------
-- -- -- -- -- -- /\/\/\/\/\/\
| | | | | | | ------------
-- -- -- -- -- -- /\/\/\/\/\/\/\
--------------
Q: What are Tensors and Spinors ?
A: You are talking about physics and applied math here.
Tensors and spinors on are just special types of array which are
used to explain 20th century physics. In a sense tensors are like
mixtures of functions and numbers. Partial derivatives feature in many
formulae involving tensors. If you are into pure maths, look at any
good book on Quadratic Forms. These will give you the group theory.
Next | Back|Top|End
Following the success of the French Revolution the new regime
co-opted some of the best scientists of the day to supervise reform of
the calendar. The new year was divided into months with names drawn
from European folk tradition. The English made fun of this innovation
by adding their own meanings. The new French years ran from September
to August.
Table YEAR_ZERO
Revolutionary English
Month nick-name
Vendemiere vintage Wheezy
Brumaire mist Sneezy
Frimaire cold Freezy
Nivose snow Slippy
Pluviose rain Drippy
Ventose wind Nippy
Germinal Showery
Floreal flowers Flowery
Prairial Bowery
Messidor Wheaty
Thermidore heat Heaty
Fructidor ripening Sweety
The French calendar was worked out by a committee of experts which
in included the great mathematician Laplace. Months all had the same
number of days. Extra days were added between some of the months to
give public holidays. Every leap year would have an extra day which
could celebrate the revolution.
Laplace ensured that his role on the calendar committee was not too
prominent because it bacame quite dangerous to express views for a
while. Two other members of the committee went to the guillotine, and
when Lavoisier the chemist was condemned his judge went on the record
as saying that the revolution had no need for scientists. Nowadays
Laplace is best known for Laplace's Equation which is of very great
importance in electro-magnetic theory.
The extremists of the time, called Jacobins, brought in two
important laws that acted as an influentual political model for the
future.
(1) Law of the Suspect.
Any person suspected of not giving one hundred support to the new
regime could be arrested and brought before a Revolutionary Tribunal.
If that person were convicted of being a counter revolutionary then
there was a mandatory death sentence.
(2) Law of the maximum.
The government could set maximum food prices by decree. Distributors
who put up prices beyond the limit were obviously to be treated as
saboteurs of the revolution.
The Jacobins also wanted to abolish torture. Their death sentences
made use of the newest technology of the time: a heavy free sliding
blade invented by Dr Guillotine. There is some evidence that
Guillotine's technology was rather more appropriate for executions than
the new fad introduced by the Americans one hundred years later. During
the 1890s debates between Siemans and Westinghouse over A.C. or D.C
electric power systems the Americans tried out wiring up condemned
criminals to the electrodes; they are still debating this application
of technology one hundred years after that. A cynic, or maybe Theodore
Kaczynski, might well add that it is a pity that Laplace did not go to
the guillotine as well as Lavoisier.
It is fairly sure that Laplace was not the only astronomer who
needed to be aware of the politics of the time. Most civilisations have
had professional astronomers from ancient times. Some of them must have
tried to get funding by predicting the fortunes of big-shots. Kepler
himself is reputed to have cast a horoscope for Wallenstein, a famous
European Warlord during the Thirty Years War (1618-48).
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Fibonacci Model 1202. Leonardo de Pisa. Liber Abaci.
Y[t+1] = Y[t]+Y[t-1]
Single population. Two cohorts.
Doubling time model. Widespread actuarial use from 1700s.
Malthus [6] popularised the idea in the 1820s.
dY/dt = K*Y
Logistic Curve. Non-linear.
dY/dt = aY-bY^2 = Y(a-bY)
Volterra Equations. 1920s Two species.
Predator and Prey.
dX/dt = aX-bXY
dY/dt = -cXY+pX
The Volterra equations remain unsolved at the time of writing.
Volterra himself was directly interested in these equations. His son in
law analysed statistics on the Adriatic fish catch. Population
modelling has generally not received much funding. There is much
commercial and political pressure to supress this sort of knowledge.
Industrial fisheries are a case in point. Scientists are generally
ignored when they recommend prudence while robber barons are keen to
exploit the benefits of science to follow fish shoals with satellite
navigation aids. In the meantime the law enforcement agencies never use
high technology to catch these kleptocratic industrial pirates but turn
their guns on desperate people trying to either to migrate or to ship
'illegal drugs'.
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The loom and the music box.
The current day meaning of a list of numbers only became common
towards the end of the last century when mathematicians started a
systematic study of linear equations and invented matrices,
determinants and tensors. The British mathematicians, Cayley and
Sylvester, were well known contributors to this field.
Ada, Countess of Lovelace [1], was an early pioneer of machine
oriented calculations on arrays. One particular array taxed her mind.
She worked on programming the calculation of the Bernoulli numbers,
These are found in the power series expansion of cos(x)/sin(x), and
x/(exp(x)-1).
Babbage had made a theoretical design of a computer to do
calculations and although his computer never worked the period saw a
whole lot of inventions for storing programs. These early methods
included rolls of material with holes in them, or rotating drums with
pins sticking out. The two methods correspond to male and female, Yin
and Yang, or N and P layers of semiconductors which stand for the
absence or presence of electrons.
The popular stored program machines of this era included textile
machinery and clockwork music boxes. The Player Piano was perhaps the
most elaborate such device. There were also early attempts to deceive
the public into believing in 'chess playing computers' where the
sponsor would hide a dimunitive chess master in an engine and get
people to play chess against it.
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Shockwave Calculations.
Einstein needed tensors in order to construct the Theory of
Relativity. From that day the 'Lords of the Array' became completely
reduced to the ranks of the proletariat. Arrays and matrices were only
taught in advanced maths and physics courses, and they had more
theoretical than practical use. Numbers were stored by writing them on
paper.
It was still easier to comission armies of manpower to handle vast
calculations. Disney studios employed hundreds of artists for its
animations. The Atom Bomb project used hundreds of human calculators to
solve some of the differential equations.
The 'National Emergency' of the Second World War saw great advances
in computing and management science. The computing community split into
two with 'Partial Differential Equations' opposed to 'Commercial Data
Processing'. There were those who naively believed that increased
computing power could make for a better society. The idea of economic
planning had been OK in wartime, and food rationing schemes had
sometimes been worked out on theoretical calculations. China and Russia
both had governments which paid lip service to the planned economy.
Whole systems of input-output equations had been invented to describe
the economy. This was often called Marxism.
Unfortunately for Soviet and Chinese statisticians these equations
and the input data were too hot to handle because any data which
reflected poorly on the performance of the regime would be supressed,
and cause the statisticians to be imprisoned or shot.
The earliest advocates of a planned economy often had to leave their
countries in order to save their own lives. Karl Popper attempts to
analyse the reason for this in his book 'The Open Society and it's
Enemies'. Both Stalin's Russia and Hitler's Nazi Germany embraced state
planning. Thinking men voted with their feet.
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Poverty of Data on the INTERNET.
Nowadays statisticians do not run such high risks of being shot.
Offending data is buried in ordure. There are plenty of subservient
think-tanks to produce all sorts of idiotic reports to justify
government policy. Nevertheless some data is so sensitive that people
will be persecuted for revealing it. Drug prices, and food and drug
safety issues are jealously guarded, and there are many half forgotten
cases of alleged corporate manslaughter.
Stanley Adams, a former Hoffman La-Roche employee, lost his liberty
and his wife when he revealed the drug company's European price fixing
arrangements. Planned profit is precious.
Also in Europe there have been several suspicious deaths of
frontline data collectors in the field of vetinary medecine. The
additions of hormones and antibiotics to animal feed have raised
concerns about health for decades, and the agri-business sector seems
to have heeded these concerns by adding good old fashioned shit to the
diets of the animals.
The reader will not see many arrays in government reports, or
elsewhere, including the Internet. More often reports are represented
as graphs or bar charts with carefully concealed scaling information.
The array that a scientist may want to access could be buried in
megabytes of Post Script code.
In real life data arrays are hard to accumulate. It needs some
discipline to keep figures for a time series for example. Budget cuts
and privatisation are the enemies of the modern statistician.
Megamergers between rival pharmaceutical companies also contribute to
the chaos. Any array has an associated size, normally the number of
elements in the array. This is important. Sometimes new drugs and
medical treatments are advocated even though there are more doctors
doing the research than patients whose treatment is being evaluated.
With the increasing power of computers it gets easier and easier to
maintain statistics but most of them only reflect the enrichment of the
elite: the profits of the big corporations and those of their immoral
dealings which they wish to disclose to their old-boys club style
regulators that run the World's capital markets. In the meantime those
responsible for the data are cajoled into efficiently operating the
machinary, rather than operating their brains.
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Bernoulli numbers just come from from long division by power series
[3]. They can be used to estimate sums by integrals. The most famous
formula in which they arise is Stirling's Approximation for n factorial
(n! = 1 x 2 x 3 .... x n-1 x n). They come as coefficients in the
expansion
oo
x --- n
------ = > B[n] x
x --- ---
e -1 n=1 n!
Z<-N P_INV A
|Inverse of series a[0]+a[1]x+a[2]x*x....
|assume a[0]=1
Z<-1 & N<-20 #ifndef"N"
AA: ->(NAA
XX:
B[ 0]= 1 1/1
B[ 1]= -0.5 -1/2
B[ 2]= 0.16666667 1/6
B[ 4]= -0.03333333 -1/30
B[ 6]= 0.02380952 1/42
B[ 8]= -0.03333333 -1/30
B[ 10]= 0.07575758 5/66
B[ 12]= -0.25311355 -691/2730
B[ 14]= 1.1666667 7/6
B[ 16]= -7.0921569 -3617/510
B[ 18]= 54.971178 43867/798
B[ 20]= -529.12424 -174611/330
B[ 22]= 6192.1232 854513/138
B[ 24]= -86580.253 -236364091/2730
B[ 26]= 1425517.2 8553103/6
B[ 28]= -27298231 -23749461029/870
B[ 30]= 6.0158087e+08 8615841276005/14322
B[ 32]= -1.5116316e+10 -7709321041217/510
B[ 34]= 4.2961464e+11 2577687858367/6
B[ 36]= -1.3711655e+13 -26315271553053477373/1919190
B[ 38]= 4.8833232e+14 2929993913841559/6
B[ 40]= -1.9296579e+16 -261082718496449122051/13530
B[ 42]= 8.4169305e+17 1520097643918070802691/1806
B[ 44]= -4.0338072e+19 -27833269579301024235023/690
B[ 46]= 2.1150749e+21 596451111593912163277961/282
B[ 48]= -1.2086627e+23 -5609403368997817686249127547/46410
B[ 50]= 7.5008667e+24 495057205241079648212477525/66
These numbers are calculated by inverting the series (exp(x)-1)/x.
The method is found in the D4 script ada.d4f. Fast methods of
evaluating these numbers were pioneered by Ramanujan who was reputed
able to do such calculations in his head.
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Zeta(k) is the sum 1/n^k for integers n >=0.
n=oo
__ 1
Zeta(s) = \ ____
/__ s
n=1 n
The zeros of Zeta(s) are distributed in a T shape in the complex
plane. Some are on the negative x axis, y=0, x=-2n and others are in a
strip 0
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Some very profound problems in mathematics have very simple
definitions. A classic example is the '3n+1' problem or the Collatz
Conjecture.
Define a function f:N->N where N is the set of positive integers.
f(n) = n/2 if n is even.
f(n) = 3n+1 if n is odd.
For example 5 is odd so f(5)=3*5+1=16. f(16)=8, f(8)=4, f(4)=2 and
f(2)=1. We also have f(1) = 4. For any function f and starting point x
the sequence x, f(x), f(f(x)) .... is known as the orbit of x under f.
In the case of the '3n+1' function these orbits are also known as 'Ulam
Numbers'. The question concerns the eventual behaviour of such
sequences: do these 'Ulam Numbers' always converge to the cycle 1 2 4 ?
At the time of writing no one knows.
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A dynamical system is a pair (X,f) where X is a set and f is a
continuous function f:X->X. For example X may be co-ordinates and
momenta of sun and planets and f a rule for computing the state of the
system at time t+1 given its state at time t. For any given start x[0]
the sequence given by x[n+1] = f(x[n]) gives the ultimate behaviour of
the system. The French mathematician Poincare invented dynamical
systems. Many important problems of maths, physics and even economics
and ecology can be reduced to the study of dynamical systems.
Since 1986 dynamical systems have served to illustrate the
limitations of mathematics as a means of predicting the real world. The
simple system z<-z^2+c defined on the complex number plane is enough to
generate the Mandelbrot set. The fractal images that people see are the
complement of the Mandelbrot set. The colours reflect the amount of
computation required to show that the iteration z<-z^2+c diverges.
The following fragment of C-language code generates the pixels
of an image that can readily be found in books on fractals.
/* dynamic system z<-z^2+c with global parameters eps, bailout */
int j_orbit(cy, cx)
double cy, cx;
{
double x = 0.0, y = 0.0;
double x1, y1, x2, y2;
int j;
for(j = 0; j < bailout; j++) {
x2= x*x; y2=y*y;
if (4.1 < x2+y2) return j;
x1 = cx + x2-y2;
y1 = cy + 2*x*y;
x = x1;
y = y1;
}
return 0;
}
References:
[1] The Theory of Numbers, 4th edition.
Hardy & Wright. pp19,22.
[2] n=p1+p2(=$1m).
David Ward.
The Guardian, 18 March 2000
[3] Ada and the First Computer
Eugene Eric Kim & Betty Alexandra Toole,
Scientific American, May 1999.
[4] Plagues. Their Origin, history and future.
Christopher Wills.
Harper Collins 1996.
[5] Prime Time
Erica Klarreich
New Scientist, 11 Nov 2000 #2264.
[6] An Essay on the Principle of Population
Malthus. Various editions from 1798-1830
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(C) Tony Goddard, Sheffield 2003
+44(0)7944 764312
http://d4maths.lowtech.org
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