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If A is a set, then the absolute complement of A (or simply the complement of A) is the set of elements not in A (within a larger set that is implicitly defined). In other words, let U be a set that contains all the elements under study; if there is no need to mention U, either because it has been previously specified, or it is obvious and unique, then the absolute complement of A is the ...
In mathematics, a relation denotes some kind of relationship between two objects in a set, which may or may not hold. [1] As an example, " is less than " is a relation on the set of natural numbers ; it holds, for instance, between the values 1 and 3 (denoted as 1 < 3 ), and likewise between 3 and 4 (denoted as 3 < 4 ), but not between the ...
The algebra of sets is the set-theoretic analogue of the algebra of numbers. Just as arithmetic addition and multiplication are associative and commutative, so are set union and intersection; just as the arithmetic relation "less than or equal" is reflexive, antisymmetric and transitive, so is the set relation of "subset".
It is emphasized that the definition of depends on context. For instance, had L {\displaystyle L} been declared as a subset of Y , {\displaystyle Y,} with the sets Y {\displaystyle Y} and X {\displaystyle X} not necessarily related to each other in any way, then L ∁ {\displaystyle L^{\complement }} would likely mean Y ∖ L {\displaystyle Y ...
The number of equivalence relations is the number of partitions, which is the Bell number. The homogeneous relations can be grouped into pairs (relation, complement), except that for n = 0 the relation is its own complement. The non-symmetric ones can be grouped into quadruples (relation, complement, inverse, inverse complement).
The complement of a reflexive relation is irreflexive—and vice versa. The complement of a strict weak order is a total preorder—and vice versa. Restriction
In the mathematics of binary relations, the composition of relations is the forming of a new binary relation R ; S from two given binary relations R and S. In the calculus of relations, the composition of relations is called relative multiplication, [1] and its result is called a relative product.
The relation > is the converse of the irreflexive kernel of , which is always a subset of the complement of , but > is equal to the complement of if, and only if, is a total order. [ a ] Alternative definitions