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Servo888
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[Discrete Math] f: A-->B; surjective? find necessary & sufficient condition.
Ok in practice for my discrete exam, I have the following problem.
Let f : A->B be a function.
a) Show that if f is surjective, then whenever g o f = h o f holds for the functions g,h : B -> C, then g =h.
b) Find a necessary and sufficient condition for f such that for any set C and any functions g,h:B->C, if g o f = h o f, then g = h
I need help at starting this problem. How do I start on a)? Here's what I know,
g o f : A -> C , so (g o f)(a) = g(f(a)),
such that (a,c) are elements in g o f <=> [tex]\exists b \in B:(a,b)\in f[/tex], [tex](b,c)\in g[/tex]
I hope that latex stuff comes out right. Anyways I've got 3 hours to figure this out. I just need a push forward, maybe some hints, or suggestions.
Ok in practice for my discrete exam, I have the following problem.
Let f : A->B be a function.
a) Show that if f is surjective, then whenever g o f = h o f holds for the functions g,h : B -> C, then g =h.
b) Find a necessary and sufficient condition for f such that for any set C and any functions g,h:B->C, if g o f = h o f, then g = h
I need help at starting this problem. How do I start on a)? Here's what I know,
g o f : A -> C , so (g o f)(a) = g(f(a)),
such that (a,c) are elements in g o f <=> [tex]\exists b \in B:(a,b)\in f[/tex], [tex](b,c)\in g[/tex]
I hope that latex stuff comes out right. Anyways I've got 3 hours to figure this out. I just need a push forward, maybe some hints, or suggestions.
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