During last year's Chess Championship, on November 11, 2016, Magnus Carlsen vs Karjakin, Mangus opted not to take the opponent's queen, taking instead the Knight, in move 24.

Figure 1: Just before Karjakin exposes his queen.

Figure 2: Carlsen can take the queen with his rook at c1.

Figure 3: Instead, Carlsen trades rook for knight.

But why?

Because they reached a detente not to trade queens. Such agreements are reached if BOTH queens are left vulnerable, and they were both vulnerable for two full moves. If you want to study more chess games, this Android application will help you. We have about 288 K games in the cloud. Feel free to study and learn from them.

You can copy a game to the clipboard to email, or to export to another application.

To install the application (you must allow third-party sources in your security settings), click:

https://github.com/jj30/ChessPGNHelper/raw/master/app/app-release.apk