Keeping the e5-pawn is important in order to resist. This mistake ends the game.

The a4-pawn is in a very bad way and this is on top of the material deficit, so White chose to resign.

White has just played 30.h4? with the likely intention of continuing 31.g5 when he would gain a large space advantage and lasting pressure. This involves calculating a simple variation that gains an exchange for a pawn and evaluating the resulting position.

White has an exposed king, his rooks lack prospects and he has weak pawns on e3 and h4, or elsewhere in case of a modification of the structure. The black knight has excellent squares on e4 and f5 and the g4-pawn is annoying. Without calculating anything we can see that White cannot be better and is probably much worse. Thus, to have played 30.h4 in a superior position was a big strategic mistake.

Threatening a check on e4. 37...Ne4+? immediately is no good because of 38.Rxe4.

White gave up without asking to see 40.Rg2 Re3+ followed by mate.

White has active pieces and a four vs three pawn majority on the kingside (the e3-pawn is neutralized by the d5-pawn and is not included). His main plan is to advance his f-pawn to gain space and improve the f1-rook’s prospects. The g3- bishop defends the e5-pawn, which will allow White to carry out the f4-f5 thrust without losing it, and if f5-f6 is also possible then the black king’s pawn cover would be decisively damaged. Black does not have an active plan available to him at the moment and will strive to block the white f-pawn.

A very strong move that provokes a weakening of the black kingside before opening the position.

Black had a curious defence, involving the sacrifice of the h6-pawn: 19...f5! 20.Qxh6 (20.exf6? Bxf6 would be strong if 21.Qxh6? wasn’t refuted by 21...Qxe3+) 20...Kf7! (with the idea of winning the queen by 21...Rh8) 21.Qh7+ Ke6 (now the threat is to repeat moves, starting with 22...Rh8) 22.Bh4! Qf7 23.Qxf7 Rxf7 24.Bxe7 Rxe7 – now White has an extra pawn and a decent advantage, but the win is far from assured.

To exchange the best black piece.

Kashdan sacrifices the e5-pawn to quickly get his rooks into play. 22.exf4, with the idea of taking on g6 and playing f4- f5 again in order to permanently eliminate the black pawns on g6, was also strong.