reserve o,m for set;
reserve C for Cartesian_category;
reserve a,b,c,d,e,s for Object of C;
reserve C for Cocartesian_category;
reserve a,b,c,d,e,s for Object of C;

theorem Th68:
  for f,k being Morphism of a,c, g,h being Morphism of b,c st Hom(
  a,c) <> {} & Hom(b,c) <> {} & [$f,g$] = [$k,h$] holds f = k & g = h
proof
  let f,k be Morphism of a,c, g,h be Morphism of b,c;
  assume
A1: Hom(a,c) <> {} & Hom(b,c) <> {};
  then [$f,g$]*in1(a,b) = f & [$f,g$]*in2(a,b) = g by Def28;
  hence thesis by A1,Def28;
end;
