...in case you would be willing to share some knowledge - what exactly is a GTO play in poker? Does it mean a Nash equilibrium strategy? Something else entirely?
Whenever I search this stuff I get practical poker strategy guides, but none of them seem to define the term haha
Two player poker is a zero sum game, where GTO play is very well-defined as just playing a Nash equilibrium strategy. The solvers try to get as close as they can to that.
Life is a lot more complicated in multiplayer poker. There are Nash equilibria, but potentially many with different payoffs, and you can't force your opponents to choose the one you're aiming for. So in that case, it's not so obvious what "optimal" means.
As for CFR adapting to opponent play: CFR could bias its compute resources towards really finely optimizing strategies for the most likely scenarios facing certain players, and it seems like this has been done during poker tournaments.
But within those situations, it would still be trying to more perfectly approximate the Nash strategy, vs. more experimental approaches which actually choose a different strategy to exploit opponent weaknesses.
Whenever I search this stuff I get practical poker strategy guides, but none of them seem to define the term haha