UGC NET CSE | June 2016 | Part 2 | Question: 1

Question

How many difference equivalence relations with exactly three different equivalence classes are there on a set with five elements?

• A. 10
• B. 15
• C. 25
• D. 30

Answer 1

answer is 25

refer http://math.stackexchange.com/questions/322738/number-of-equivalence-relations-on-a-finite-set

to get some idea

Comments

three different equivalence classes

means - partitionaing of 5 elements into 3 non- empty set . right sir ??

Answer 2

Ans: C

ref: https://gateoverflow.in/90931/equivalence-relaton