Why would GIB do this?

[bixby]

Link to deal

 

The deal linked above is from yesterday's ACBL MP Daylong #1. Like most tables, I played in 3NT by N. After the first four tricks it seemed clear that I was headed for +660, but just for practice I thought I would play out my winners in a way that would squeeze East if East had the DK, even though that was nearly impossible on the bidding and play so far (East had made a weak jump overcall of 2H and was known to have started with the HKJ and the CKQ, so it could hardly have the DK as well). To my complete surprise, at trick 10 East discarded the HK, allowing me to claim the rest for +690. I got 99% instead of the 67.7% I would have had for +660.

 

Why would East do that? East saw West discard on a heart lead at trick 3, so East knows that North has the HAQ remaining, and East can see the H5 remaining in dummy. As far as I can tell, the discard of the HK is a zero percent play that can only lose and never gain. Even if East thought North had the DK, discarding the HK is at best indifferent -- it would neither gain nor lose. But if West has the DK (as in fact it did), discarding the HK costs a trick.

 

This seems like an error that a robot player with perfect memory couldn't make. Why would GIB do this?

[smerriman]

It happens now and then, and nobody knows why :(

[pescetom]

It happens now and then, and nobody knows why :(

 

Maybe only today? :unsure:

See the other post.