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By Eduardo Sardeiro | March 14th 2009 08:20 PM | 18 comments | Print | E-mail | Track Comments
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About Eduardo Sardeiro

I'm a brazilian scientist and automation systems consultant, who studies intelligence in its different aspects, from the Artificial Intelligence, to the Extra-Terrestrial Intelligence passing, surely... Full Bio

Letter S

ince the beginnings of humanity, the task of counting was always very important. The development of human society had always been based on counts. 

In the beginning, the simple Arithmetic was enough: counts of people, food, game, stones, days... 

There were many symbols to represent the counts. The Roman Numerical System was one of them, but it wasn't practical. The set of mathematical symbols that we use today was originated with the Hindus, was improved by Arabs, and it's a Decimal System just because we have 10 fingers! 

Representation of Natural Numbers

While we survived only with the counting of whole numbers, several imperfections went unnoticed. One of them, and of which solution brought significant progress, was the lack of the zero number! The zero number, for many centuries, was an inconceivable truth: after all, even if there were people without fingers, it was difficult to imagine a practical use for zero. In few words: the zero always existed, but we weren't prepared for it, at the beginning of civilization. 

The sufficient maturity came with the abacus, a Chinese invention proper to do large counts. For the abacus' processes to work correctly, the knowledge of zero (no account), had to be well established. 

Abacus

The acceptation of zero ( Zero) brought a lot of novelties. Starting with expansion of our numerical system, because such as the zero, the negative numbers became evident too. Thus, it became easier to comment about previous days, lost points, regressive sums and other kinds of counting... Our universe was no more contained into the Natural Numbers [N]. But, since those days, it became possible to describe the universe with the Whole Numbers [Z], positive and negative. 

Line of Whole Numbers

But that was not enough. New measures were not represented at that scale yet. There were the fractional numbers that, for a long time, was the cause of fight between the men. While it was possible to round the fractions, the agreements happened. But numbers like square roots, pi number and other rational numbers, made us understand that the application of our scale of Whole Numbers was extremely limited: in a straight line, which could be all positive and negative numbers, it was also possible to align intermediate numbers, like very small fractions, as many as they were possible to imagine. Concomitantly, the existence of infinitesimal quantities, had led us to the infinitely large quantities and vice versa, through its divisions by the unit ( Infinite). 

In this way, the set of Real Numbers [R] arose, those that could be understood and therefore used, because our universe was no more contained into the Whole Numbers. 

Line of Rational Numbers

And we live in peace in our Mathematical Cosmo for many and many generations... No one could imagined that we would have more surprises. Our Line of Numbers looked like perfect... 

It was when the Algebra arose, and with it the possibilities of working with numerical representations instead of numbers themselves! The equations could be handled with some abstraction, independent of the quantities of which they meant. And, once a day, the quantities related to the square root of negative numbers ( Imaginary Number) arrived! They were the new "black holes" of our Mathematical Reason. 

Luckily, by then, always when we faced a mathematical problem without solution, our understanding of the world increased. Thus, our Line of Rational Numbers became the plan of Complex Numbers [C]. Our simple numbers, that once upon a time was used to count sheeps, in that moment, got an unprecedented spatial scale. We gain understanding that any number, though simple, is always a couple of real and imaginary values. 


Plan of Complex Numbers

So, since the last centuries of the second millennium a.C., we have learned to live with the idea that, in the universe, there were numbers whose value was totally real, and whose numbers could also contain an imaginary percentage. 

However, the humanity began to behold and to pursue its own limits! It didn't take time to we perceived that the whole thing would not stop there. In the Age of Reason who would be satisfied in a Numerical System on the plan, since we already had the domain of Geometry? Moreover, new technologies require knowledges beyond the simple imagination. 

The new beat came from the possibility to raise any number into an imaginary power. What would mean, for example, a number one raised into an imaginary power? This problem come from the rotation of vectors, in computer graphics. The Quaternions  ( Quaternion) emerged as an alternative to the first Set of Numbers called HyperComplex

And hardly our Plan of Complex Numbers had become the Space of Quaternions, it already spoke about the hyperspace of the HyperComplex Numbers [H]. The numerical dimensions exceeded even the fourth dimension... They went so beyond that mixed up with own numeric infinite! The graph below, with a sphere in the center, is merely illustrative! There is no way to represent correctly the fourth, the fifth and the n-th dimensions in a plan or even into space! 

Space of HyperComplex Numbers

Yep... now it looks like that we can live in peace in our Mathematical Cosmo... Our reason overcame itself. Apparently, nothing more is necessary to expand in our Numerical System. 

But we need to fill the gaps of discoveries that have been left behind. Our simple Arithmetic, for example, dances, jumps up, does zip-zap, does twist, makes handstand, and so on when it is applied within all these sets! 

The base is well established
! Now we must continue to build the Mathematics!

Comments

logicman's picture
since the beginnings of humanity, the task of counting was always very important.


With respect, I am inclined to believe that the 'one-many' concept must have developed long before the counting concept. I mean by this that our ancestors probably used words for 'one' and 'many' long before abstracting the metanumeric concept of 'number' from, presumably, the tally. If a dog has three bones and I take one away, the dog will undoubtedly notice. But do dogs understand 'number' thereby?

There may be a parallel with language: children acquire many words before they acquire the metalinguistic concepts 'word' and 'meaning'. Perhaps human grasp of number and language evolved together following their discovery as metacategories?

Anyone interested in higher dimensions of space may enjoy reading Robert Heinlein's And He Built a Crooked House.

esardeiro's picture

Thanks for the comment!

This my first quick review just show the state of the art of the Mathematics. I intend to write about other topics in a simple way, showing how some mathematical problems 'unsolvable' can be resolved.

The issue of initial learning, be mathematical or purely linguistic, can be understood with Neural Networks. The algorithm called backpropagation gives us some tips on this kind of learning, which should be similar to what occurs in dogs.

But there is another kind of learning that occurs at the semantics level. Neural-Networks Catalysts show us how this can occur. It even gives us some important tips on how occurs the acquirement of knowledge like Common Sense, Mathematical Theories and Commonplace Dialogues.



Gerhard Adam's picture
The algorithm called backpropagation gives us some tips on this kind of learning, which should be similar to what occurs in dogs.

In truth, the brain seems to come equipped with a basic number sense that is separate and distinct from calculating ability. 

Though people often think of mathematics as a pinnacle intellectual achievement of humankind, research reveals that some intuition about numbers, counting and mathematical ability is basic to almost all animals.
http://www.sciencedaily.com/releases/2008/09/080907211940.htm



Steve Davis's picture
Great article.

This is the first time I read an article linking a quartenion with a number raised into an imaginary power (j = 1^i).
Could you provide any reference book about this?

esardeiro's picture
The most important studies in this regard were conducted by Leonhard Euler (1707-1783) and William Rowan Hamilton (1805-1865).
You can read about at
QUATERNIONS AND ROTATION SEQUENCES: A Primer with Applications to Orbits, Aerospace and Virtual Reality
J. B. Kuipers
And at John Baez website:
http://plus.maths.org/issue32/features/baez/

Johannes Koelman's picture
Eduardo -- great to see someone taking the effort to create instructive math articles here on ScientificBlogging. Kudos for that.

On the quaternions:
I think anon is correct: you may indeed want to check the literature. You can not construct the quaternion units i, j, k by defining j = 1^i. Continuing along this line, how would you define k? The link to the interview with John Baez does not hint at your approach to the quaternions being correct.

esardeiro's picture

Hi Johannes!

Thanks for the comment! I'm sorry to answer your message with a long delay, but A lot of things have happened here in São Paulo. And this makes my studies about these subjects more difficult.
I recommended this literature as an introduction about quaternions. Sure, this literature doesn't define j = 1^i exactly.

In fact, the number of dimensions of the Universe of Numbers is what determines the equivalences. Thus, if the Universe of Numbers has 3 dimensions (the natural axe, the imaginary axe (i) and the quaternion axe (k), as represented by the cube above) can be defined that 1^i = k and i^k = 1.

Similarly, if the universe of numbers has 5 dimensions (the natural axe, the imaginary axe (i), the quaternion axe (j), the quaternion axe (k) and the quaternion axe (l)), then 1^i = k, i^k = j, k^j = l e l^i = 1 (Note that there is a circular equivalence here).

Using this notation and the Analitical Geometry, you can determine other information about the number as the absolute value, related area, related cube and so on.

These equivalences require that the operation of multiplication don't be commutative, just as the Theory of Quaternions explains.

It must exist another way to deal with numbers of type 1^i. However, in my researchs, it work well.

Best regards,



rholley's picture
This comment has got me thinking.  I have recently been much exercised with how, almost single-handedly, Euler worked out a complete theory of complex numbers.[1]  Not only are they closed and also obey the normal axioms of arithmetic under addition, subtraction, multiplication and division, thereby forming a field, but are also closed under exponentiation, so that the logarithm of any complex number is itself a complex number.

Because of their non-commutative multiplication, quaternions are not a field, but rather a division ring.  Slightly expanding the Wikipedia article on quaternions:



Even though they contain copies of the complex numbers, they are not an associative algebra over the complex numbers because multiplying a quaternion by a complex number is not always commutative.


The norm makes the quaternions into a normed algebra, and even into a composition algebra and a unital Banach algebra. Composition algebras are very rare. Hurwitz's theorem states that there are only four composition algebras over the real numbers: Real numbers themselves, Complex Numbers, H or Quaternions (the H stands for Hamilton), and Octonions. Because it is possible to divide quaternions, they form a division algebra. This is a structure similar to a field except for the commutativity of multiplication. Finite-dimensional division algebras over the real numbers are also very rare. The Frobenius theorem states that there are exactly three: R, C, and H.



All of which does not take us any further towards answering the question: can one define (in a sensible way) the logarithm of a quaternion, or can one raise a quaternion to the power of a quaternion and still, hopefully, get a quaternion?

I am following this up, but since I do not live in Dublin, I cannot trying crossing Brougham Bridge, where William Rowan Hamilton famously got his inspiration.

[1] Euler: the Master of Us All by William Dunham http://www.amazon.com/Euler-Master-Dolciani-Mathematical-Expositions/dp/0883853280

 

esardeiro's picture

Hi Robert!

Thank you very much by the explanations! I was very busy in the last weeks and I couldn't receive that messages.

I'm trying to use the Parcelatories to explain why multiplication of quartenions cannot be commutative. I think it is possible  to do this.

Best Regards,



rholley's picture
Nine Zulu Queens Ruled China.  Have you heard this mnemonic? It stands for

N Natural numbers
Z Integers
Q Rational numbers
R Real numbers
C Complex numbers

I learned it from Unknown Quantity: A Real and Imaginary History of Algebra by John Derbyshire.

This article does, I think, qualify as a "Brief History" in the Stephen Hawking sense, but the actual history of mathematics is much more complicated.  For example, let us take ZERO in its two separate uses as a placeholder and as a number.  As a number along with positive and negative integers, it was well established in India by Brahmagupta (598 –  670), but Al Khwarizmi (790 – 840), the inventor of algebra, only took on board the use of zero as a placeholder, and wrote about this in his "Book on Indian Reckoning" along with his "Reckoning by Algebra", both of which reached Europe about three centuries later.

So people in the Middle East and Europe struggled with algebra using only positive numbers for centuries.  Being a bit of a mathematical Fossil Hunter, I found a 15th century German quoting a Frenchman saying:

“As the doll would be an eagle, the donkey a lion, the she-ape a queen – so would zero be a digit.”

The trouble is, these "Brief Histories" make it sound all so easy, so that eminent mathematicians, especially French ones, seem to think that one can fast-track children into becoming mathematicians, as in this snippet from the introduction to "Geometry in a Modern Setting" by Gustave Choquet. 

"As soon as possible, the child must think of the set R of numbers as a totally ordered, commutative field: he must realize that when he is carrying out calculations, he is only using a small number of the properties of addition and of multiplication, the ones which mathematicians call the axioms for totally ordered commutative fields."

Concerning such pedagogy, the eminent Russian mathematician V.I.Arnold really read the riot act to an audience in Paris, quoting the case of a child who was asked

"What is 2+3?"

The child replied

"The same as 3+2, because addition is commutative."

without understanding what the question was actually about.




esardeiro's picture
My friends and pupils like your mnemonic very much! Thanks!

rholley's picture

Logarithms of quaternions?  I have the answer, from the horse's mouth, so to speak.  The following is from

On a New Species of Imaginary Quantities, Connected with the Theory of Quaternions
Author: W. R. Hamilton
Source: Proceedings of the Royal Irish Academy (1836-1869), Vol. 2 (1840 - 1844), pp. 424-434

and here it is.  In other words, you can exponentiate a quaternion, just as you can a matrix.  But if you do the reverse, and take logs, the log of a product of quaternions does not equal the sum of the logs of the individual quaternions.  (Hardly surprising, given that multiplication of quaternions is not commutative.)



Hi Eduardo!
I read and reread this text and the comments. Your writing is excellent.
In the case of imaginary numbers, what do you say about i^i?
Is there imaginary numbers raised to another imaginary?
Cya

rholley's picture
Hello Abbie,

Roberto here!

Your question just popped up on my email, and I've got just the two slides for you from my Math History lectures.  They're related to a discovery by Johann Bernoulli (1667 – 1748):





Hope you like them.  In fact, not long afterward Euler showed that complex numbers are closed under exponentiation, so that any complex number raised to a complex number is a complex number (bearing in mind that reals and pure imaginaries are also included in the field of complex numbers.)  Here we have i^i having a real value!

esardeiro's picture
Hi Abbie! Hi Robert!

My intention when I wrote this text was only to introduce the current State of the Art of the Mathematics. It was to be a short one. I didn't comment, for example, about Rational neither Binaries Numbers.

I didn't expect to enter into this questions for now, because there are still some aspects of the Euler's work which I intend to investigate.

Anyway, the text informed by Robert tells us about the absolute value of the Hypercomplex Numbers.

Even the value of an imaginary number, like this (ii), can be obtained through a simple transformation. It follows:

Let's us suppose initially 1i = j, belonging to a Set of Numbers with three dimensions (n, i, j), where n, i and j belong to the set of Real Numbers.

If we raise this number to the i-th power we have:

(1i)i = 1i*i = 1-1 = 1/1 = 1

So (1i)i = 1, and if 1i = j, we have ji = 1.

In the same way, if we have -j, or -1i, and if we raise this number to the i-th power, we have:

(-1i)i = -1i*i = -1-1 = 1/-1 = -1

And then -ji = -1.

On the other hand, we have the number ii where:

ii = (-11/2)i = (-1)i * 1/2 = (-1)i/2 = (-1i)1/2 = -j1/2.

That is, ii is equal to -j1/2, in the Set of Numbers with three dimensions.

Although there may be Sets of Numbers with infinite dimensions, the basis all of them is the Set of Natural Numbers. In physical phenomena, for example, if it's determined the accuracy of measurements, they all behave like Big Integers Numbers which must be divided by powers of ten.

So I've been continuing to this brief history of Mathematics with the Theory of Parcelatories.

Best regards!

Thank you, Eduardo and Robert!
This'll be important for the work I'm doing here this week.
By the way, how can I put exponents in the equations as subscripts here?

esardeiro's picture
I'm happy with this, Abbie!
If you have new questions about this topic, you are welcome to send them!
You can use the html tags <sup></sup>.
Example: i<sup>i</sup> is show like ii

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