# Mathematics

File:Euclid.jpg
Euclid, detail from "The School of Athens" by Raphael.

Mathematics can be defined as the logically rigorous study of topics such as quantity, structure, space, and change. Another view, held by many mathematicians, is that mathematics is the body of knowledge justified by deductive reasoning, starting from axioms and definitions.

Mathematics is used throughout the world in fields such as science, engineering, surveying, medicine, and economics. These fields both inspire and make use of new discoveries in mathematics. New mathematics is also created for its own sake, without any particular application in view.

The word "mathematics" comes from the Greek μάθημα (máthēma) meaning science, knowledge, or learning, and μαθηματικός (mathēmatikós), meaning fond of learning. It is often abbreviated math in North American English and maths in Commonwealth English .

## Inspiration, pure and applied mathematics, and aesthetics

Mathematics arises wherever there are difficult problems that involve quantity, structure, space, or change. At first these were found in commerce, land measurement and later astronomy; nowadays, all sciences suggest problems studied by mathematicians, and many problems arise within mathematics itself. Newton invented infinitesimal calculus and Feynman his Feynman path integral using a combination of reasoning and physical insight, and today's string theory also inspires new mathematics. Some mathematics is only relevant in the area that inspired it, and is applied to solve further problems in that area. But often mathematics inspired by one area proves useful in many areas, and joins the general stock of mathematical concepts. The remarkable fact that even the "purest" mathematics often turns out to have practical applications is what Eugene Wigner has called "the unreasonable effectiveness of mathematics."

As in most areas of study, the explosion of knowledge in the scientific age has led to specialization in mathematics. One major distinction is between pure mathematics and applied mathematics. Within applied mathematics, two major areas have split off and become disciplines in their own right, statistics and computer science.

Many mathematicians talk about the elegance of mathematics, its intrinsic aesthetics and inner beauty. Simplicity and generality are valued. There is beauty also in a clever proof, such as Euclid's proof that there are infinitely many prime numbers, and in a numerical method that speeds calculation, such as the fast Fourier transform. G. H. Hardy in A Mathematician's Apology expressed the belief that these aesthetic considerations are, in themselves, sufficient to justify the study of pure mathematics.

## Notation, language, and rigor

Most of the mathematical notation we use today was not invented until the 16th Century. Before that, mathematics was written out in words, a painstaking process that limited mathematical discovery. Modern notation makes mathematics much easier for the professional, but beginners often find it daunting. It is extremely compressed: a few symbols contain a great deal of information. Like musical notation, modern mathematical notation has a strict syntax and encodes information that would be difficult to write in any other way.

Mathematical language also is hard for beginners. Even common words, such as or and only, have more precise meanings than in everyday speech. Mathematicians, like lawyers, strive to be as unambiguous as possible. Also confusing to beginners, words such as open and field have been given specialized mathematical meanings, and mathematical jargon includes technical terms such as "homeomorphism" and integrable. It was said that Henri Poincaré was only elected to the Académie Française so that he could tell them how to define automorphe in their dictionary. But there is a reason for special notation and technical jargon: mathematics requires more precision than everyday speech. Mathematicians refer to this precision of language and logic as "rigor".

Rigor is fundamentally a matter of mathematical proof. Mathematicians want their theorems to follow from axioms by means of systematic reasoning. This is to avoid mistaken 'theorems', based on fallible intuitions, of which many instances have occurred in the history of the subject (for example, in mathematical analysis). The level of rigor expected in mathematics has varied over time; the Greeks expected detailed arguments, but by the time of Isaac Newton the methods employed were less rigorous. Problems inherent in the definitions used by Newton would lead to a resurgence of careful analysis and formal proof in the 19th century. Today, mathematicians continue to argue among themselves about computer-assisted proofs. Since errors can be made in a computation, such proofs may not be sufficiently rigorous.

Axioms in traditional thought were 'self-evident truths', but that conception is problematic. At a formal level, an axiom is just a string of symbols, which has an intrinsic meaning only in the context of all derivable formulas of an axiomatic system. It was the goal of Hilbert's program to put all of mathematics on a firm axiomatic basis, but according to Gödel's incompleteness theorem every (sufficiently powerful) axiomatic system has undecidable formulas; and so a final axiomatization of mathematics is unavailable. Nonetheless mathematics is often imagined to be (as far as its formal content) nothing but set theory in some axiomatization, in the sense that every mathematical statement or proof could be cast into formulas within set theory.

## Is mathematics a science?

Carl Friedrich Gauss referred to mathematics as "the Queen of the Sciences".Template:Rf If one considers science to be strictly about the physical world, then mathematics, or at least pure mathematics, is not a science. Karl Popper believed that mathematics was not experimentally falsifiable and thus not a science.Template:Fact An alternative view is that certain scientific fields (such as theoretical physics) are mathematics with axioms that are intended to correspond to reality. In fact, the theoretical physicist, J. M. Ziman, proposed that science is public knowledge and thus includes mathematics.  In any case, mathematics shares much in common with many fields in the physical sciences, notably the exploration of the logical consequences of assumptions. Intuition and experimentation also play a role in the formulation of conjectures in both mathematics and the (other) sciences. As experimental mathematics continues to grow in importance within mathematics, and computation and simulation play an ever bigger role in both the sciences and mathematics, the objection that mathematics does not utilize the Scientific Method becomes weaker and weaker.

The opinions of mathematicians on this matter are varied. While some in applied mathematics feel that they are scientists, those in pure mathematics often feel that they are working in an area more akin to logic and that they are, hence, fundamentally philosophers. Many mathematicians feel that to call their area a science is to downplay the importance of its aesthetic side, and its history in the traditional seven liberal arts; others feel that to ignore its connection to the sciences is to turn a blind eye to the fact that the interface between mathematics and its applications in science and engineering has driven much development in mathematics. One way this difference of viewpoint plays out is in the philosophical debate as to whether mathematics is created (as in art) or discovered (as in science). It is common to see universities divided into sections that include a division of Science and Mathematics, indicating that the fields are seen as being allied but that they do not coincide. In practice, mathematicians are typically grouped with scientists at the gross level but separated at finer levels.

## Overview of fields of mathematics

As noted above, the major disciplines within mathematics first arose out of the need to do calculations in commerce, to understand the relationships between numbers, to measure land, and to predict astronomical events. These four needs can be roughly related to the broad subdivision of mathematics into the study of quantity, structure, space, and change (i.e., arithmetic, algebra, geometry, and analysis). In addition to these main concerns, there are also subdivisions dedicated to exploring links from the heart of mathematics to other fields: to logic, to set theory (foundations) and to the empirical mathematics of the various sciences (applied mathematics).

The study of quantity starts with numbers, first the familiar natural numbers and integers and their arithmetical operations, which are characterized in arithmetic. The deeper properties of whole numbers are studied in number theory.

The study of structure began with investigations of Pythagorean triples. Neolithic monuments on the British Isles are constructed using Pythagorean triples. Eventually, this led to the invention of more abstract numbers, such as the square root of two. The deeper structural properties of numbers are studied in abstract algebra and the investigation of groups, rings, fields and other abstract number systems. Included is the important concept of vectors, generalized to vector spaces and studied in linear algebra. The study of vectors combines three of the fundamental areas of mathematics, quantity, structure, and space.

The study of space originates with geometry, beginning with Euclidean geometry. Trigonometry combines space and number. The modern study of space generalizes these ideas to include higher-dimensional geometry, non-Euclidean geometries (which play a central role in general relativity) and topology. Quantity and space both play a role in analytic geometry, differential geometry, and algebraic geometry. Within differential geometry are the concepts of fiber bundles and calculus on manifolds. Within algebraic geometry is the description of geometric objects as solution sets of polynomial equations, combining the concepts of quantity and space, and also the study of topological groups, which combine structure and space. Lie groups are used to study space, structure, and change. Topology in all its many ramifications may be the greatest growth area in 20th century mathematics.

Understanding and describing change is a common theme in the natural sciences, and calculus was developed as a most useful tool. The central concept used to describe a changing quantity is that of a function. Many problems lead quite naturally to relations between a quantity and its rate of change, and the methods of differential equations. The numbers used to represent continuous quantities are the real numbers, and the detailed study of their properties and the properties of real-valued functions is known as real analysis. These have been generalized, with the inclusion of the square root of negative one, to the complex numbers, which are studied in complex analysis. Functional analysis focuses attention on (typically infinite-dimensional) spaces of functions. One of many applications of functional analysis is quantum mechanics. Many phenomena in nature can be described by dynamical systems; chaos theory makes precise the ways in which many of these systems exhibit unpredictable yet still deterministic behavior.

Beyond quantity, structure, space, and change are areas of pure mathematics that can be approached only by deductive reasoning. In order to clarify the foundations of mathematics, the fields of mathematical logic and set theory were developed. Mathematical logic, which divides into recursion theory, model theory, and proof theory, is now closely linked to computer science. When electronic computers were first conceived, several essential theoretical concepts in computer science were shaped by mathematicians, leading to the fields of computability theory, computational complexity theory, and information theory. Many of those topics are now investigated in theoretical computer science. Discrete mathematics is the common name for the fields of mathematics most generally useful in computer science.

An important field in applied mathematics is statistics, which uses probability theory as a tool and allows the description, analysis, and prediction of phenomena where chance plays a role. It is used in all the sciences. (Many statisticians, however, do not consider themselves to be mathematicians, but rather part of an allied group.) Numerical analysis investigates computational methods for efficiently solving a broad range of mathematical problems that are typically much too large for a human's capacity; it includes the study of rounding errors or other sources of error in computation.

## Major themes in mathematics

An alphabetical and subclassified list of mathematics articles is available. The following list of themes and links gives just one possible view. For a fuller treatment, see areas of mathematics or the list of mathematics lists.

### Quantity

Quantity starts with counting and measurement.
 Failed to parse (Can't write to or create math temp directory): 1, 2, \\ldots \\, Failed to parse (Can't write to or create math temp directory): \\ldots, -1, 0, 1, \\ldots \\, Failed to parse (Can't write to or create math temp directory): \\frac{1}{2}, \\frac{2}{3}, 0.125,\\ldots \\, Failed to parse (Can't write to or create math temp directory): \\pi, e, \\sqrt{2},\\ldots \\, Failed to parse (Can't write to or create math temp directory): i, 3i+2, e^{i\\pi/3},\\ldots \\, Natural numbers Integers Rational numbers Real numbers Complex numbers
NumberHypercomplex numbersQuaternionsOctonionsSedenionsHyperreal numbersSurreal numbersOrdinal numbersCardinal numbersp-adic numbersInteger sequencesMathematical constantsNumber namesInfinityBase

### Structure

Pinning down ideas of size, symmetry, and mathematical structure.
 Failed to parse (Can't write to or create math temp directory): 36 \\div 9 = 4 File:Elliptic curve simple.png File:Rubik float.png File:GroupDiagramD6.png File:Lattice of the divisibility of 60.png Arithmetic Number theory Abstract algebra Group theory Order theory
MonoidsRingsFieldsLinear algebraAlgebraic geometryUniversal algebra

### Space

A more visual approach to mathematics.
Algebraic geometryDifferential topologyAlgebraic topologyLinear algebraCombinatorial geometryManifolds

### Change

Ways to express and handle change in mathematical functions, and changes between numbers.
 File:Integral as region under curve.png File:Vectorfield jaredwf.png Failed to parse (Can't write to or create math temp directory): \\frac{d^2}{dx^2} y = \\frac{d}{dx} y + c File:Limitcycle.jpg File:LorenzAttractor.png Calculus Vector calculus Differential equations Dynamical systems Chaos theory
AnalysisReal analysisComplex analysisFunctional analysisSpecial functionsMeasure theoryFourier analysisCalculus of variations

### Foundations and methods

Approaches to understanding the nature of mathematics.
 Failed to parse (Can't write to or create math temp directory): P \\Rightarrow Q \\, File:Venn A intersect B.png File:MorphismComposition-01.png Mathematical logic Set theory Category theory
Foundations of mathematicsPhilosophy of mathematicsIntuitionismConstructivismProof theoryModel theoryReverse mathematics

### Discrete mathematics

Discrete mathematics involves techniques that apply to objects that can only take on specific, separated values.
 Failed to parse (Can't write to or create math temp directory): \\begin{matrix} (1,2,3) & (1,3,2) \\\\ (2,1,3) & (2,3,1) \\\\ (3,1,2) & (3,2,1) \\end{matrix} File:Fsm moore model door control.jpg File:Caesar3.png File:6n-graf.png Combinatorics Theory of computation Cryptography Graph theory
Computability theoryComputational complexity theoryInformation theory

### Applied mathematics

Applied mathematics aims to develop new mathematics to help solve real-world problems.
Mathematical physicsMechanicsFluid mechanicsNumerical analysisOptimizationProbabilityStatisticsMathematical economicsFinancial mathematicsGame theoryMathematical biologyCryptographyMathematics and architectureMathematics of musical scales

### Important theorems

These theorems have interested mathematicians and non-mathematicians alike.
See list of theorems for more
Pythagorean theoremFermat's last theoremGödel's incompleteness theoremsFundamental theorem of arithmeticFundamental theorem of algebraFundamental theorem of calculusCantor's diagonal argumentFour color theoremZorn's lemmaEuler's identityclassification theorems of surfacesGauss-Bonnet theoremQuadratic reciprocityRiemann-Roch theorem.

### Important conjectures

See list of conjectures for more

These are some of the major unsolved problems in mathematics.
Goldbach's conjectureTwin Prime ConjectureRiemann hypothesisPoincaré conjectureCollatz conjectureP=NP? – open Hilbert problems.

### History and the world of mathematicians

See also list of mathematics history topics

History of mathematicsTimeline of mathematicsMathematiciansFields medalAbel PrizeMillennium Prize Problems (Clay Math Prize)International Mathematical UnionMathematics competitionsLateral thinkingMathematics educationMathematical abilities and gender issues

## Common misconceptions

Mathematics is not a closed intellectual system, in which everything has already been worked out. There is no shortage of open problems.

Pseudomathematics is a form of mathematics-like activity undertaken outside academia, and occasionally by mathematicians themselves. It often consists of determined attacks on famous questions, consisting of proof-attempts made in an isolated way (that is, long papers not supported by previously published theory). The relationship to generally-accepted mathematics is similar to that between pseudoscience and real science. The misconceptions involved are normally based on:

• misunderstanding of the implications of mathematical rigour;
• attempts to circumvent the usual criteria for publication of mathematical papers in a learned journal after peer review, often in the belief that the journal is biased against the author;
• lack of familiarity with, and therefore underestimation of, the existing literature.

The case of Kurt Heegner's work shows that the mathematical establishment is neither infallible, nor unwilling to admit error in assessing 'amateur' work. And like astronomy, mathematics owes much to amateur contributors such as Fermat and Mersenne.

Mathematics is not accountancy. Although arithmetic computation is crucial to accountants, their main concern is to verify that computations are correct through a system of doublechecks. Advances in abstract mathematics are mostly irrelevant to the efficiency of concrete bookkeeping, but the use of computers clearly does matter.

Mathematics is not numerology. Numerology uses modular arithmetic to reduce names and dates down to numbers, but assigns emotions or traits to these numbers intuitively or on the basis of traditions.

Mathematical concepts and theorems need not correspond to anything in the physical world. In the case of geometry, for example, it is not relevant to mathematics to know whether points and lines exist in any physical sense, as geometry starts from axioms and postulates about abstract entities called "points" and "lines" that we feed into the system. While these axioms are derived from our perceptions and experience, they are not dependent on them. And yet, mathematics is extremely useful for solving real-world problems. It is this fact that led Eugene Wigner to write an essay on The Unreasonable Effectiveness of Mathematics in the Natural Sciences.

Mathematics is not about unrestricted theorem proving, any more than literature is about the construction of grammatically correct sentences. However, theorems are elements of formal theories, and in some cases computers can generate proofs of these theorems more or less automatically, by means of automated theorem provers. These techniques have proven useful in formal verification of programs and hardware designs. However, they are unlikely to generate (in the near term, at least) mathematics with any widely recognized aesthetic value.

## Notes

Template:Ent Wolfgang Sartorius von Waltershausen: Gauss zum Gedächtniss, 1856. (Gauss zum Gedächtnis 1965 reprint by Sändig Reprint Verlag H. R. Wohlwend: ISBN 3-253-01702-8, ASIN: B0000BN5SQ).

## References

• Kline, Morris, Mathematical Thought from Ancient to Modern Times, Oxford University Press, USA; Paperback edition (March 1, 1990). ISBN 0195061357.

## Further reading

• Benson, Donald C., The Moment Of Proof: Mathematical Epiphanies, Oxford University Press, USA; New Ed edition (December 14, 2000). ISBN 0195139194.
• Boyer, Carl B., A History of Mathematics, Wiley; 2 edition (March 6, 1991). ISBN 0471543977. — A concise history of mathematics from the Concept of Number to contemporary Mathematics.
• Courant, R. and H. Robbins, What Is Mathematics? : An Elementary Approach to Ideas and Methods, Oxford University Press, USA; 2 edition (July 18, 1996). ISBN 0195105192.
• Davis, Philip J. and Hersh, Reuben, The Mathematical Experience. Mariner Books; Reprint edition (January 14, 1999). ISBN 0395929687.— A gentle introduction to the world of mathematics.
• Gullberg, Jan, Mathematics--From the Birth of Numbers.W. W. Norton & Company; 1st edition (October 1997). ISBN 039304002X. — An encyclopedic overview of mathematics presented in clear, simple language.
• Hazewinkel, Michiel (ed.), Encyclopaedia of Mathematics. Kluwer Academic Publishers 2000. — A translated and expanded version of a Soviet mathematics encyclopedia, in ten (expensive) volumes, the most complete and authoritative work available. Also in paperback and on CD-ROM, and online .
• Pappas, Theoni, The Joy Of Mathematics, Wide World Publishing; Revised edition (June 1989). ISBN 0933174659.
• Template:Cite book

## External links

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Mathematics".