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To investigate the left distributivity of set subtraction over unions or intersections, consider how the sets involved in (both of) De Morgan's laws are all related: () = = () always holds (the equalities on the left and right are De Morgan's laws) but equality is not guaranteed in general (that is, the containment might be strict).
Given sets X and Y, a heterogeneous relation R over X and Y is a subset of { (x,y) | x∈X, y∈Y}. [ 2 ] [ 22 ] When X = Y , the relation concept described above is obtained; it is often called homogeneous relation (or endorelation ) [ 23 ] [ 24 ] to distinguish it from its generalization.
A prime ordinal is an ordinal greater than 1 that cannot be written as a product of two smaller ordinals. Some of the first primes are 2, 3, 5, ... , ω, ω + 1, ω 2 + 1, ω 3 + 1, ..., ω ω, ω ω + 1, ω ω + 1 + 1, ... There are three sorts of prime ordinals: The finite primes 2, 3, 5, ... The ordinals of the form ω ω α for any ordinal α.
Set-builder notation can be used to describe a set that is defined by a predicate, that is, a logical formula that evaluates to true for an element of the set, and false otherwise. [2]
Just as arithmetic features binary operations on numbers, set theory features binary operations on sets. [9] The following is a partial list of them: Union of the sets A and B, denoted A ∪ B, is the set of all objects that are a member of A, or B, or both. [10] For example, the union of {1, 2, 3} and {2, 3, 4} is the set {1, 2, 3, 4}.
For example, the union of three sets A, B, and C contains all elements of A, all elements of B, and all elements of C, and nothing else. Thus, x is an element of A ∪ B ∪ C if and only if x is in at least one of A, B, and C. A finite union is the union of a finite number of sets; the phrase does not imply that the union set is a finite set ...
Naive set theory is any of several theories of sets used in the discussion of the foundations of mathematics. [3] Unlike axiomatic set theories, which are defined using formal logic, naive set theory is defined informally, in natural language.
The collection of convex subsets of a vector space, an affine space, or a Euclidean space has the following properties: [9] [10] The empty set and the whole space are convex. The intersection of any collection of convex sets is convex. The union of a sequence of convex sets is convex, if they form a non-decreasing chain for inclusion.