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