Search results
Results from the WOW.Com Content Network
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 ...
For example, "is a blood relative of" is a symmetric relation, because x is a blood relative of y if and only if y is a blood relative of x. Antisymmetric for all x, y ∈ X, if xRy and yRx then x = y. For example, ≥ is an antisymmetric relation; so is >, but vacuously (the condition in the definition is always false). [11] Asymmetric
Lawson-Perfect's approach is to represent each part of a question as a function of the answer to the previous part. That is, if a student answer's "x" for part a, the correct answer to part b is "f(x)." No matter what the student puts for part a, the corresponding answer for part b can be calculated quickly.
It is easy to show that if a union-closed family contains a singleton {} (as in the example above), then the element must occur in at least half of the sets of the family. If there is a counterexample to the conjecture, then there is also a counterexample consisting only of finite sets. Therefore, without loss of generality, we will assume that ...
In mathematics, an element that is greater than or equal to every element of a given set, used in the discussion of intervals, sequences, and functions. upward Löwenheim–Skolem theorem A theorem in model theory stating that if a countable first-order theory has an infinite model, then it has models of all larger cardinalities, demonstrating ...
In constructive mathematics, "not empty" and "inhabited" are not equivalent: every inhabited set is not empty but the converse is not always guaranteed; that is, in constructive mathematics, a set that is not empty (where by definition, "is empty" means that the statement () is true) might not have an inhabitant (which is an such that ).
As reformulated, it became the "paving conjecture" for Euclidean spaces, and then a question on random polynomials, in which latter form it was solved affirmatively. 2015: Jean Bourgain, Ciprian Demeter, and Larry Guth: Main conjecture in Vinogradov's mean-value theorem: analytic number theory: Bourgain–Demeter–Guth theorem, ⇐ decoupling ...
The axiom of replacement allows one to form many unions, such as the union of two sets. However, in its full generality, the axiom of union is independent from the rest of the ZFC-axioms: [citation needed] Replacement does not prove the existence of the union of a set of sets if the result contains an unbounded number of cardinalities.