CHESS#1244

The last instalment of this column featured an "anti-computer position" composed by Sir Roger Penrose. That illustrates a hole in engine-evaluation. Black is massively ahead in material. But the position is totally locked and white can just shuffle around for a draw. 

Every engine will give an absurd evaluation, assessing black as winning.  But if a computer is tasked to defend the white side, it will flawlessly find the right moves and draw, even while it pessimistically assesses its position to be lost!  

In practical play, engines often fail to evaluate fortress positions (say, when a lone queen is trying to win against a Rook anchored by a pawn, which is well-defended by the king). But they do find the best movies for both sides. 

A third situation where computers can be uncertain is positional sacrifices. Typically, a player may sacrifice a little material (a pawn, or the exchange for a pawn) for some compensation without forcing sequences. Computers can make the wrong assessments. However, there has been a great deal of improvement, and sometimes modern engines even make positional sacrifices.  

Where engines do really  "fail" is in playing and assessing slow build-ups behind locked pawn chains  in closed positions. For example, even strong engines misread Kings Indian Defence situations where players attack slowly on opposite flanks. Engines will rate these positions as roughly equal until suddenly, one side wins. An analogy could be the Brazilian "beautiful game" where greats like Garrincha and Pele bamboozled defences by suddenly slowing down pace of attack.   

Chessbase India celebrated its one-year anniversary, more or less by holding an online blitz event with 3 minutes plus zero increment control. This is just about fast enough to prevent egregious cheating. That drew 148 players, including six GMs and 12 IMs. Rohit Lalith Babu won first place and Rs 10,000, with a perfect 9/9 score. 

Harika Dronavalli (Elo 2539) plays the Sigeman Invitational in Malmo, Sweden. She's the lowest rated in a six-player round-robin, featuring  Pavel Eljanov, Baadur Jobava, Nigel Short, Nils Grandelius and Erik Blomqvist. Meanwhile, Pentala Harikrishna, Anish Giri, Michael Adams, Ding Liren, Yu Yangyi and Peter Svidler settle into battle at the DT News Cup in Shenzhen. And the huge Sharjah Masters Open is also on, with a large  Indian contingent. 

The DIAGRAM, BLACK TO PLAY,  is one of the most famous of positions (Martin Ortueta Vs Jose Sanz , Madrid  1993). The game  supposedly went 1.-- Rxb2!! 2. Nxb2 c3  and now [ if 3. Nd3 c4 +]  

But after 3. Rxb6 c4!! 4. Rb4 a5! (0-1). A fabulous  queening combination and even modern engines take quite a few seconds to find the winning idea. Sadly, it might never have actually been played if research by chess historians is correct. 

Devangshu Datta is an  internationally rated chess and correspondence chess player