Definitions Flashcards
A set containing no elements
Null or empty set
A ___ is a collection of distinct objects, none of which is the ___ itself
Set
A set A is said to be a ______ of B if every element if A is also an element of B
Subset
A set A is said to be equal to set B if
A is a subset of B and B is a subset of A
Theorem 1
There is only one empty set
A _____ is an object consisting of two sets called its ______ set and its ____ set
Graph
Vertex
Edge
The edge set may be _____
Empty
The vertex set is a ______, ________ set
Finite
Non empty
Elements of the edge set are ___-element subsets of the ______ set
Two
Vertex
The elements of a vertex set are called ________ and the elements of the edge set are called _____
Vertices
Edges
If {X,Y} is an edge of a graph, we say that {X,Y} _____ or ________ the vertices X and Y, and that X and Y are ________ to one another
Joins
Connects
Adjacent
The edge {X,Y} is ________ to each of X and Y, and each of X and Y is ________ to {X,Y}
incident
Two edges incident to the same vertex are called ________ edges
adjacent
A vertex incident to no edges at all is ________.
isolated
Two graphs are equal if
They have equal vertex sets and equal edge sets
