Q is epi in the category of rings. (ii) Show that kernels are monic and are unique up to isomorphism. (iii) In Groups, show that monics are...

Q is epi in the category of rings. (ii) Show that kernels are monic and are unique up to isomorphism. (iii) In Groups, show that monics are injections and kernels are monics with normal image. What are epis and cokernels? 2. (Colimits and van Kampen) (i) What is the coproduct of groups usually called? (ii) Let H be a subgroup of groups G and G . What is the pushout G H G usually called? (iii) When is the coproduct of groups G and H finite?