It's interesting in chess theory when two authors go down the same line in a specific opening. At one point one author gives a move, the other one didn't consider. Here are two examples: 1.d4 f5 2.Nf3 Nf6 3.g3 e6 4.Bg2 Be7 5.O-O O-O 6.c4 d6 7.b3 a5 8.Bb2 a4 9.b4 is a recommendation of Sielecki in his course "Keep it Simple: 1. d4" whereupon Williams has some more thoughts/moves in his "The Killer Dutch Rebooted" course. 1.d4 Nf6 2.Nc3 d5 3.Bf4 e6 4.e3 Bb4 5.Bd3 c5 6.dxc5 Nbd7 7.Ne2 a6 8.Bg3 Nh5 9.e4 this line seems to be in both Sielekies "Lifetime Repertoires: The Nimzo-Ragozin" and Williamses "The Jobava London System" but Sielecki gives 9 ...Nxc5 which does not seem to be included in Williamses course. I know this is like a theoretical fight. Theory A against theory B, but I want to see those two players fight against each other somewhere in an online match, be it on youtube, twitch or whatever. The safe and sound theoretician IM Christof Sielecki vs the "crazy" fighting GM Simon Williams. Those two should do a match against each other, just because their playing style is so different.