Where is the line?

Originally posted by lausey
Would it be against the rules if someone was to use previous lines (generated from an engine) on a completed game, and apply this to the same position in an in progress game?

It would be against the rules if that analysis was done whilst the current game was in progress but it would not be against the rules if you analysed your existing completed games with an engine before starting a game that then followed the lines of your past games (not uncommon of course) and you then used an improvement discovered earlier.

Having done that you are of course correct that the game mods would not be able to tell the difference between a single move (or even a couple of moves) discovered earlier and engine assistance but , and this is probably the important point, it is probable that after a few moves you would leave this prepared line and now you are on your own. So if you continue to make engine moves then it is probable you are no longer using previously generated analysis but are in fact using an engine.