commutativity and associativity not perfect

[leesugil]

there are still expressions that are not completely reduced even if it's obvious to eyes. i'm leaving this note in rush so apologies for lack of bringing specific examples. the current temporary design for MVP feels like blind shooting when reducing terms and evaluating it. that's reflected in how the main "process" loop is placed, yet still not doing a complete job reducing terms. maybe we need to take more fundamental, core combinatorial consideration.

i suggest a combinatorially complete way to consider comparing all terms of a given mathematical expression.

[leesugil]

will start by making some combinatorial functions

[leesugil]

here's a non-working example