Function check_goal 

pub fn check_goal(goal: &Term) -> bool

Check if a goal is provable by congruence closure.

This is the main entry point for the CC tactic. It builds an E-graph, adds hypothesis equalities, propagates congruences, and checks if the conclusion follows.

Supported Goals

• Direct equalities: (Eq a a) succeeds by reflexivity
• Implications: (implies (Eq x y) (Eq (f x) (f y))) succeeds by congruence
• Multiple hypotheses: (implies (Eq a b) (implies (Eq b c) (Eq a c)))

Returns

true if the goal is provable by congruence closure, false otherwise.