CSP is no search problem (but it induces one)

I do not think that a CSP should be formalized as a search problem as csp.en.tex does. Rather make an extstructure from smglom/complexity.../problem.en.tex. The relation to search problems should be given by a view (take the CSP-semantics from the AI lecture as a basis). Also, constraints should be formalized some more, as relations between n domains --> define order.

Adapt from https://en.wikipedia.org/wiki/Constraint_satisfaction_problem that has all the necessary parts.