"Could a human beat a computer at chess?"
Like, now. 20 years after Kasparov. Could someone do it? The question feels daring somehow.
Exercise to the reader: prove that at most one color can have a winning strategy.
Since the problem is open, it could be that one side has a winning strategy. It's even theoretically possible there's a winning strategy simple enough for a human to follow. In which case, yes, a human could beat computers with 100% dominance--as long as the human is allowed to choose which color to play.
If you're asking how a human can contrive a scenario to beat Stockfish/Leela, that seems like just a conversation that devolves into what is and isn't too contrived.
Big showcase computer-human matches ended in the mid-2000s. That's about the point when people realized it was hopeless to try to beat computers. The best you could do back then was draw, by playing extremely defensive "anti-computer" chess (positions where the pawns clog up the board, making short-term tactics useless, and making long-term strategy more important). But with modern engines (particularly AlphaZero, which understands positional chess much better than previous engines), even anti-computer chess doesn't work. Now, the top players actually rave about the games played by AlphaZero. Magnus Carlsen has said he wants to play like AlphaZero.
For a more quantitative comparison, these are the Elo scores of the top chess engines: https://www.computerchess.org.uk/ccrl/404/
A difference of 400 Elo points means that the better player should score 0.9 (where 1=win, 0.5=draw, 0=loss). The top computers are about 3600 Elo nowadays, compared to 2870 for the best human (Magnus). It's difficult to directly compare human and computer Elos, but this comparison is based on computer-human games played in the late 1990s to early 2000s. Still, computers are many hundreds of Elo points above the very best human players.
If you start from a winning position, even something as stupid as a random-mover will eventually play a perfect sequence of moves and win, given enough attempts.
However humans are not very good at being random, so this may not apply :)
` It was a massively parallel, RS/6000 SP Thin P2SC-based system with 30 nodes, with each node containing a 120 MHz P2SC microprocessor, enhanced with 480 special purpose VLSI chess chips.`
I misread at first thinking it was grossly 30GHz summed but it's only 3.6GHz (I know, gross maths). So yeah the comparison is apt.. a recent SoC can outperform this old behemoth.
1. https://www.computerchess.org.uk/ccrl/404/cgi/compare_engine...
But generally, humans have accepted computer supremacy in chess pretty well. Everyone realizes that a better chess-playing entity exists out there (in everyone's pocket, in fact). That doesn't make the competition between human players less exciting. It's still a match to prove that you're better than the person sitting across the board from you, and it's still incredibly impressive to see how deeply and accurately the top players can calculate, or how much knowledge they have of the game.