I've found a fundamental difference in the use of
G2:=CopyGraph(G):
and
G2:=G:
where G is a Graph in the GraphTheory package.
If I change G2 in the first case, G remains the same.
If I change G2 in the second case, G changes together with G2.
(The same happens when G is an input parameter in a procedure. Normally formal parameters cannot be changed, but if G is a graph there is no error message when changing G).
This is totally different from happens with normal assignments of variables, like
x:=3:
y:=x:
x:=4:
y; 3
Could someone explain why and how these assignments are different?
