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Which of these relations on the set of all functions from Z to Z are equivalence relations?

(a) $\{(f,g) \mid f(1)=g(1)\}$

(b) $\{(f,g) \mid f(0)=g(0) \text{ or } f(1)=g(1)\}$

(c) $\{(f,g) \mid f(x)-g(x)=1 \text{ for all } x \in \textbf{ Z} \}$

In this question, what does it mean by f(1) = g(1) and f(1) - g(1)? And how it satisfies all the conditions (Symmetric, Transitive and Reflexive) of equivalence relation. Actually I cannot able to analyze when the relations defined on set of function. If anyone describe a bit it would helpful.
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(a) equivalence relation

f has one element ,say i.e. 1 . Two function (f and g) merging in one element . Relation will be (1,1)

(b) not reflexive

f  has 2 elements , say i.e. 1,2 .But relation is (1,1) or (2,2) , but may not both

(c) not reflexive, not symmetric

distance between same element of f to g is 1 . But distance between g to f is -ve , which is not possible. So, it is not even symmetric
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