I'm not yet working on any project with them; I just looked up a basic definition. I am studying linguistics but haven't gotten to semantics yet. Semantic nets look like they use logic that I'm familiar with.
Logic of semantic nets is based on logic of ANY net (graph): base unit is - two nodes and rib between them.
Then we must interpret what is nodes and what is ribs.
As semantic for us is the branch of linguistics so nodes here are words.
Particularly in ASSOCIATIVE semantic nets rib serves as fixations of the fact of associative relation between words the rib connects.