In a set, the number of times an element occurs does not matter. If you want to keep track of the number of occurrences, you need a multiset.SO in the end we have a set which contains 3 values {5,5,25}

* It's not good to use the same variable name for two entities. In Y(P), Y is a function that takes a path, but in the right-hand side, Y is a number.Y(P) = {Y|Y ϵ Z+ and Y contains minimum values of all the I number of paths}

What i mean is that P is a path between source and destination nodes(B & C in this example), I is the number of paths that exist between

two nodes(I=3 in the above case), Y contains set of minimum link values of all the I number of paths({5,5,25}) in this case, which belong to set of

positive integers Z+.

* The left-hand side Y(P) takes a particular path P as an argument, so the right-hand side must be some characteristic of this path. However, the right-hand side is a property of all paths.

* "Y ϵ Z+ and Y contains minimum values": If Y is a number, it cannot contain anything. Only sets can.

* The right-hand side has a variable I that does not occur in the left-hand side. It is not clear what its value should be.

I would first come up with a definition of a path (e.g., a sequence of edges with some properties). Then I would define a function MinEdge(P) for a path P. Then, given a network N and two nodes B and C, one can define

Y(N,B,C) = {MinEdge(P) | P is a path in N between B and C}

Alternatively,

Y(N,B,C) = {n in Z^+ | n = MinEdge(P) for some path P in N between B and C}