Challenge 1: Running solve/1 on parent/2 and grandparent/2 — Possible Solution
====================================================================

meta_demo.pl:

solve(true) :- !.
solve((A, B)) :- !, solve(A), solve(B).
solve(A) :- clause(A, Body), solve(Body).

parent(tom, bob).
parent(tom, liz).
parent(bob, ann).
parent(liz, jim).
grandparent(X, Z) :- parent(X, Y), parent(Y, Z).

Queries:

    ?- solve(parent(tom, bob)).
    true.

    ?- solve(grandparent(tom, Z)).
    Z = ann ;
    Z = jim.

Explanation:
solve(parent(tom, bob)) falls through to the third clause:
clause(parent(tom, bob), Body) finds the matching fact directly, with
Body unified with true, and solve(true) then succeeds via the first
clause's cut. solve(grandparent(tom, Z)) follows the exact trace the
chapter walked through -- clause/2 finds grandparent's own rule body,
the conjunction is split into two solve/1 calls via the second
clause, and each parent/2 lookup is resolved via clause/2 exactly the
same way, ultimately backtracking through both of tom's
grandchildren, ann and jim, matching the chapter's own stated result
exactly.

WHY THIS WORKS AS AN ANSWER
------------------------------
This runs the meta-interpreter unmodified against the chapter's own
facts and rule, confirming both a simple fact query and the full
grandparent/2 trace produce exactly the results the chapter's own
hand-traced walkthrough predicted.