I asked a question few minutes ago, and when I saw the answer to my question, I found that I had explained my question wrongly (so the answer was not what I wanted to know). So I decided to write new ...
Given category C, Its morphism category D means a category that has 1) "morphisms of C" as its objects 2) "pair (f,g) s.t. the diagram(square) commutes" as its morphisms The above definition is ...
I am very much interested in listening to the history behind the exact sequence. We know that the exact sequence is sequence of objects with morphisms such that image of one morphism equals to the ...