Are all main lines and variations of chess openings necessarily SOUND?.
I mean since we can't know all possible games, unique games, which are so large, about 10⁴⁰, how can I be sure that all "book", "theory" openings are SOUND?
I mean that, may be, some "book" openings may be UNSOUND?
Strong CHESS Engines may, to a limit, can examine all "book", "theory" chess openings.
Sound chess openings should lead to a decisive, not drawish, games. If a white opening, should lead to white win. If a black defence, should lead to black win.
Sound book, theory white opening should lead to white win, provided that no inaccuracy, mistake or blunder, from the white. And the same runs for the black defence. Note that possible games are very large, approximately 10⁴⁰ unique games.
I suggest that this is why Super Grandmasters, stopped at 2850 Elo, no even the world champion could beat any strong chess engine.
Of course we exclude inaccuracies, mistakes, and blunders.