"... Strategic trap is of a different character. By masking our own strategic plan, we entice our oponent to take measures that in fact help us with our task. [Let us consider this game.]

<16.Nxd5?> 16.Rfe1 would have been better. Trying 16...exd5 instead of <16...cxd5> was dangerous for 17.Bc2 with Qd3 afterwards.

<20.Qe3 a5> The position is now completely even. Black has a weak pawn on e6, but strong Bf6. He can also compensate White pressure on c-file by counteraction on K-side (g5).

<21.a3!> is the first interesting <psychological trap>. During the foregoing play, Black could not realy exchanged Bxe5 as White would retake with his queen. White thus leaves his Bb3 open and tempts Black to swap on e5. He correctly recons that, to neutralize the e6-weakness, Black will have to pay a too-high a strategic price of being left with the 'bad-bishop' only. <21...Bxf5?> White speculation came though. It would have been better to play Kh8 with later g5.

<fxe4 Bd7> Black chooses a simple defensive plan. He intends to exchange heavy piecess on the c-file. It would probably be impossible to convert White small advantage afterwards.

<Kh1!> In the connection to the following moves a very cunning plan connected with a <psychological trap>. White inteds to occupy the c-file. Should he do so immediately, however, it would only lead to exchanges. He therefore maneuvers his piecess so as if he intends to decide the game by a K-side attack. He expects that his oponent will worry about his preparations and take excessive protective measures. This can leave the c-file witout adequate defense.

<27.Bd3> Of course, not 27.g4? Rxc2! 28.Rxc2 fxg4 with subsequent Be4+. The push g4 is quite benign even now, but the threat puts Black under psychological duress. <28.h3> Once again, White seemingly threattens 29.g4. In reality, this move is not dangerous. Black can take on g4 and then efficiently stop the f4-f5 breakthough by Rcf7. By his demonstration, however, White entices Black to take additional prophylactic measures. After the <28...Rcf7?> White takes the posetion of the c-file. Thelen's calculation was psychologically well underwritten by F. Treybal's known propensity for cautious style of play and dilligent prevention of sharp castle attacks.

<29.Rc1 Qd8> The fight for c-file is, after the preceding error, decided. If 30...Rc7, then 31.Rxc7 Qxc7 32.Rc2 and 33.Qc1. In the rest, White accurate converts his positional advantage.

<31.Kh2> Prevents possible g5 by preparing g3. <34.Rc6> The threat is 35.Rd6 and 36.Rcc6. <39...Be8> An error in time-pressure after which Black soon ends up in a position without good moves. Of course, other continuations also could not have saved the game. <40...Rxc8> Or 40...Bxb5 41.Rxb8 Rxb8 42.Rc8+ Rxc8 43.Qxc8+ Kf7 44.Qb8 Be8 45.a4! etc.