prolog nondeterministic clause

In Prolog, a nondeterministic clause is a clause that can have multiple solutions or outcomes. These clauses typically use backtracking to explore all possible solutions to a query.

For example, consider the following Prolog rule:

foo(X) :- bar(X).
foo(X) :- baz(X).

If we query `foo(X)`, Prolog will first try to satisfy the goal `bar(X)`. If that fails, it will backtrack and try to satisfy `baz(X)` instead. If both clauses have valid solutions, Prolog will return multiple solutions for `foo(X)`.

Nondeterministic clauses are a powerful feature of Prolog that allow for more expressive and flexible rule-based programming. However, they can also introduce complexity and performance issues, especially when dealing with large search spaces.