Complex sentence: The match AlphaGo versus Lee Sedol is very reminiscent of the famous 1997 chess match Deep Blue versus Garry Kasparov, where IBM's Deep Blue computer's defeat of reigning champion Garry Kasparov is seen as the symbolic point where computers became better than humans at chess.
Split into simpler sentences: The match AlphaGo versus Lee Sedol is comparable to the 1997 chess match Deep Blue versus Garry Kasparov. There IBM's Deep Blue computer's defeat of reigning champion Garry Kasparov is seen as the symbolic point where computers became better than humans at chess.