How many reflexive relations are there on a set with 5 elements?
Answer and explanation
Correct answer: A. 2^20
- Step 1: All 5 pairs (a, a) must be present; the other 20 pairs are free. Step 2. So there are 2^20 reflexive relations. Answer: 2^20. Why not the others: 2^25 is what you get if you count all relations. 2^5 is what you get if you use 2^n. 2^15 is what you get if you count symmetric relations.
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