Definitions Flashcards
Define a subset.
A is a subset of B if (for all x)(x in A implies x is in B)
Define Universal Set
The set of all elements is a set or group under consideration.
Index Set
A set whose members label members of another set.
Cartesian Product
A x B = {(x,y)| x is in A, y is in B}
Relation on A
A relation on A is a subset of A x A.
Partial Order
A relation on S with properties of being reflexive, anti-symmetric and transitive.
Function
A relation from A to B in which each member of A appears exactly once as a first component.
Injective Function (one to one)
Let f: A -> B. Then f is injective if f(a) = f(b) thus implies a = b.
Surjective Function (onto)
Let f: A -> B. Then f is surjective if the codomain and range of f are the same. That is B = {f(x)|x is in A}.
Bijective Function
A function that is both injective and surjective.
T/F. The composition of two bijective functions is bijective.
True.
Bezouts Theorem.
Let a and b be nonzero integers and let d=gcd(a,b). Then there exists integers m and n such that ma + nb = d.
Valid Argument
The conjunction of the first n statements is said to imply the final statement. Thus P1^P2^…Pn => Q.
Variable
A symbol that stands for a member of a collection.
Predicate
A statement that describes the property of a variable.