Common Robot Defending Error

[calm01]

Playing with 3 robots the following losing behaviour is frequently seen by a defending robot. It is quite amusing to see, as it is a defensive error often indulged in by human players.

 

The trump suit is spades. You are West with a spade holding of K105 with AQJ8 of spades in dummy (North),

 

A spade is led by declarer through you towards dummy. What do you do? It is rarely right to play the King! But people do and the robot often does also!

 

If the suit is trumps, declarer might intend to play the Ace to draw a second round of trumps to prevent a defensive ruff. Or if the suit is not trumps declarer may have a singleton and cannot afford a loser in the suit. Or declarer may be desperate to get a guaranteed entry to dummy for a more critical other suit finesse or suit development or avoidance play. Also declarer may have a singleton and intend a ruffing finesse on the way back. Another reason to withhold the King is to make declarer waste an entry to hand to take a second finesse.

 

So it normally demonstrates a death wish to play the King as a defender in this situation.

 

I have dubbed this strategy of playing the King "Group Captain Syndrome". In the Second World War the attrition rate for fighter pilots was so high, many preferred the certainty of death by flying into a mountain side to the uncertainty but high probability of death by continuing missions.

 

A Group Captain was a senior commissioned officer in the Royal Air Force.

 

Is it about time the robots defence was demoted to that of a more junior and more sane rank?

[barmar]

I believe it's due to them using double dummy solvers to guide the defense. The bot assumes declarer is also playing double dummy, so it will always play the suit correctly. So as far as it's concerned, it's not giving anything up by inserting the King, since it "knows" that declarer isn't going to try cashing the Ace.

 

Do I have this right, Ari?