I am trying to understand some code from Vladimir Kolmogorov's excellent Graph cut library and I have a question regarding graph construction. Say I have a system of binary variables and I need to represent the following cut costs
E(0, 0) E(0, 1)
E(1, 0) E(1, 1)
Furthermore assume these energies are:
A A
0 0
and the two variables are x and y and the source and sink nodes are represented by s and t:
Now, as I see it for E(0, 0), I will need an edge from x to t and from y to t. They have the capacity A. So if both these edges are cut, both x and y belong to the source node (associated with label 0). So something like:
s
x y
\ /
\ /
\ /
\ /
t
Now for E(0, 1), I will need another edge going from s to y also with capacity A, so now the Graph looks something like:
s
\
\
\
\
x y
\ /
\ /
\ /
\ /
t
Now my question is since s->y has capacity A and y->t has capacity A, can I remove these two edges without changing the minimum cut on this graph? The reason I ask is that this construction is indeed given by a single edge from x to t (in the source code from Kolmogorov's library) and I cannot understand this construction.