Answer:
An equivalence relation R is a binary relation that is reflexive, symmetric and transitive.
Explanation:
An equivalence relation R is a binary relation that is reflexive, symmetric and transitive.
Reflexive:
R is said to b reflexive if a R a
Symmetric:
R is said to be symmetric if a R b implies b R a
Transitive:
R is said to be transitive if a R b, b R c implies a R c
Given: Let R be the relation consisting of all pairs (x,y) such that x and y are strings of uppercase and lowercase English letters with the property that for every positive integer n, the nth characters in x and y are the same letter, either uppercase or lowercase.
To prove:
R is an equivalence relation.
Reflexive:
As the nth characters in x and x are the same letter, R is reflexive
Symmetric:
If nth characters in x and y are the same letter then clearly nth characters in y and x are the same letter
Transitive:
If nth characters in x and y are the same letter and nth characters in y and z are the same letter then nth characters in x and z are the same letter.
So, R is an equivalence relation.