FACTOID # 178: There are more known reptile species in Australia than in all other listed countries combined.
 
 Home   Encyclopedia   Statistics   Countries A-Z   Flags   Maps   Education   Forum   FAQ   About 
 
WHAT'S NEW
RECENT ARTICLES
More Recent Articles »
 

FACTS & STATISTICS    Simple view

  1. Select countries to view: (hold down Control key and click to select several)

     

     

    Compare:

     

     

  1. Select fact or statistic: (* = graphable)

     

     

     

  2. (OPTIONAL) Compare to statistic: (both need to be graphable)

     

     

     

  3. View result as:

     

       
(OR) SEARCH ALL encyclopedia, stats & forums:   

Encyclopedia > Symmetry in mathematics

Symmetry in mathematics occurs not only in geometry, but also in other branches of mathematics. Square with symmetry group D4 Symmetry is a characteristic of geometrical shapes, equations, and other objects; we say that such an object is symmetric with respect to a given operation if this operation, when applied to the object, does not appear to change it. ... Wikibooks Wikiversity has more about this subject: School of Mathematics Wikiquote has a collection of quotations related to: Mathematics Look up Mathematics on Wiktionary, the free dictionary Wikimedia Commons has more media related to: Mathematics Bogomolny, Alexander: Interactive Mathematics Miscellany and Puzzles. ...


A function of n variables may be invariant under certain permutations of the variables. These permutations form a group, a symmetry group. In mathematics, a group is a set, together with a binary operation, such as multiplication or addition, satisfying certain axioms, detailed below. ... The symmetry group of an object (e. ...


For example, a2c + 3ab + b2c remains unchanged under interchanging of a and b.


In the case of a symmetric function, all permutations give the same value. A symmetric matrix, seen as a function of the row- and column number, is an example. The second order partial derivatives of a suitably smooth function, seen as a function of the two indexes, is another example. See also symmetry of second derivatives. In mathematics, the theory of symmetric functions is part of the theory of polynomial equations, and also a substantial chapter of combinatorics. ... In linear algebra, a symmetric matrix is a matrix that is its own transpose. ... In mathematics, the symmetry of second derivatives refers to the possibility of interchanging the order of taking partial derivatives of a function f(x1, x2, ..., xn) of n variables. ...


A relation is symmetric iff the corresponding boolean-valued function is a symmetric function. In mathematics, a binary relation R over a set X is symmetric if it holds for all a and b in X that if a is related to b then b is related to a. ... ↔ ⇔ ≡ For other possible meanings of iff, see IFF. In mathematics, philosophy, logic and technical fields that depend on them, iff is used as an abbreviation for if and only if. Common alternative phrases to iff or if and only if include Q is necessary and sufficient for P and P... Boolean Dealing only with the two logical values: true (1) and false (0). ...


An binary operation is commutative if the operator, as function of two variables, is a symmetric function. Symmetric operators on sets include the union, intersection, and symmetric difference. In mathematics, a binary operation, or binary operator, is a calculation involving two input quantities and one kind of a specific operation. ... Mathematical meaning In mathematics, especially abstract algebra, a binary operation on a set S is commutative if for all x and y in S. Otherwise, the operation is noncommutative. ... In set theory and other branches of mathematics, the union of a collection of sets is the set that contains everything that belongs to any of the sets, but nothing else. ... In mathematics, the intersection of two sets A and B is the set that contains all elements of A that also belong to B (or equivalently, all elements of B that also belong to A), but no other elements. ... In mathematics, the symmetric difference of two sets is the set of elements which are in one of either set, but not in both. ...


From the form of an equation one may observe that certain permutations of the unknowns result in an equivalent equation. In that case the set of solutions is invariant under any permutation of the unknowns in the group generated by the aforementioned permutations. For example, for the equation (a-b)(b-c)(c-a)=10, for any solution (a,b,c), permutations (a b c) and (a c b) can be applied giving additional solutions (b,c,a) and (c,a,b).


By considering the coordinate space we can consider the symmetry in geometric terms. In the case of three varables we can use e.g. Schoenflies notation for symmetries in 3D. In the example the solution set is geometrically in coordinate space at least of symmetry type C3. If all permutations were allowed this would be C3v. If only two unknowns could be interchanged this would be Cs. A discrete point group in 3D is a finite symmetry group in 3D that leaves the origin fixed. ...


More generally one can also consider other objects than functions and equations, and other operations than permutations of variables that leave the object unchanged. Again these operations form a group; for an algebraic object, one uses the term automorphism group instead of symmetry group. The whole subject of Galois theory deals with well-hidden symmetries of fields. In fact, prior to the 20th century, groups were synonymous with transformation groups (i.e. group actions). It's only during the early 20th century that the current abstract definition of a group without any reference to group actions was used instead. In mathematics, an automorphism is an isomorphism from a mathematical object to itself. ... In mathematics, Galois theory is a branch of abstract algebra. ... In abstract algebra, a field is an algebraic structure in which the operations of addition, subtraction, multiplication and division (except division by zero) may be performed, and the same rules hold which are familiar from the arithmetic of ordinary numbers. ... This article is about the mathematical concept. ...


A concept related to symmetry is duality (mathematics). In mathematics, duality has numerous meanings. ...

Contents


Randomness

The idea of randomness, without clauses, suggests a probability distribution with "maximum symmetry" with respect to all outcomes. In mathematics, a probability distribution assigns to every interval of the real numbers a probability, so that the probability axioms are satisfied. ...


In the case of finite possible outcomes, symmetry with respect to them implies a discrete uniform distribution. In probability theory and statistics, the discrete uniform distribution is a discrete probability distribution that can be characterized by saying that all values of a finite set of possible values are equally probable. ...


In the case of a real interval of possible outcomes, maximum symmetry with respect to them corresponds to a continuous uniform distribution. In mathematics, the continuous uniform distributions are probability distributions such that all intervals of the same length are equally probable. ...


In other cases, such as "taking a random integer" or "taking a random real number", only little symmetry is possible, there is not a particular probability distribution providing maximum symmetry, so that probability distribution should be specified.


There is one type of isometry in one dimension that may leave the probability distribution unchanged, that is reflection in a point, for example zero.


A possible symmetry for randomness with positive outcomes is that the former applies for the logarithm, i.e., the outcome and its reciprocal have the same distribution.


For a "random point" in a plane or in space, one can choose an origin, and consider a probability distribution with circular or spherical symmetry, respectively.


Skew-symmetry

A function of two variables is skew-symmetric if f(y,x) = - f(x,y). The property implies f(x,x) = 0. A skew-symmetric matrix, seen as a function of the row- and column number, is an example. This is the Yin-yang symbol or Taijitu (太極圖), with black representing yin and white representing yang. ... This is the Yin-yang symbol or Taijitu (太極圖), with black representing yin and white representing yang. ... Taoists Taijitu The concept of yin and yang (Traditional Chinese: 陰陽; Simplified Chinese: 阴阳; pinyin: ; Korean: Um-yang; Vietnamese: Âm-Dương) originates in ancient Chinese philosophy and metaphysics, which describes two primal opposing but complementary forces found in all things in the universe. ... In linear algebra, a skew-symmetric (or antisymmetric) matrix is a square matrix A whose transpose is also its negative; that is, it satisfies the equation: AT = −A or in component form, if A = (aij): aij = − aji   for all i and j. ...


The property is also called antisymmetry and, in the case of operator notation, anticommutativity. In set theory, the adjective antisymmetric usually refers to an antisymmetric relation. ... A mathematical operator (typically a binary operator, represented by *) is anticommutative if and only if it is true that x * y = −(y * x) for all x and y on the operators valid domain (e. ...


In the definition of an antisymmetric relation, "minus" is replaced by "not", and the condition is necessarily relaxed, to be required only in the case x ≠ y. The corresponding 2D set has a special kind of geometric "symmetry". In mathematics, a binary relation R on a set X is antisymmetric if, for all a and b in X, if a is related to b and b is related to a, then a = b. ...


More generally, a figure may be such that a particular involution (reflection in a point or line, or e.g. a circle reflection) interchanges e.g. black and white. For example, this applies for the yin and yang symbol with respect to point inversion. In mathematics, an involution is a function that is its own inverse, so that f(f(x)) = x for all x in the domain of f. ... In mathematics, a mapping w = f(z) is angle-preserving or (more usually) conformal at a point z0, if it preserves oriented angles between curves through z0, as well as their orientation, i. ... Taoists Taijitu The concept of yin and yang (Traditional Chinese: 陰陽; Simplified Chinese: 阴阳; pinyin: ; Korean: Um-yang; Vietnamese: Âm-Dương) originates in ancient Chinese philosophy and metaphysics, which describes two primal opposing but complementary forces found in all things in the universe. ...


Symmetry in probability theory

In probability theory, from symmetry of a sample space corresponding symmetry of the probability distribution may be derived. Probability theory is the mathematical study of probability. ... In probability theory, the sample space, often denoted S, Ω or U (for universe), of an experiment or random trial is the set of all possible outcomes. ...


See also



 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments
Please enter the 5-letter protection code

Want to know more?
Search encyclopedia, statistics and forums:

 


Lesson Plans | Student Area | Student FAQ | Reviews | Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms.