Mastering the set-theoretical notation of a binary relation

The set-theoretical notation of a binary relation is based on the notion of "ordered pairs". A relation aRb with a,b belonging to a set A, is express in set theoretical notation as “(a,b)”, in which the first element is in relation to the second.

For instance, the following relation

(cRb, dRa, bRd)

That applies to the elements of the set

A = {a,b,c,d}

Can be defined as

R = {(c,b), (d,a), (b,d)}

Exercise

Which one of the following set-theoretical notations represents the following relation on the set A = {a,b,c,d}:

dRc, bRa, dRb, aRd, bRb

That is not the right answer. Remember: a binary relation is represented using ordered pair (e.g., dRc is represented by «(d,c)» and, more importantly, not «(c,d)»).

That is not the right answer. Remember: a binary relation is represented using ordered pair (e.g., dRc is represented by «(d,c)» and, more importantly, not «(c,d)»).

That is not the right answer. Remember: a binary relation is represented using ordered pair (e.g., dRc is represented by «(d,c)» and, more importantly, not «(c,d)»).

Good job, you got it right! You're already on your way to becoming a mathematical psychologist!