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Why does GIB consistently underlead Aces ?? Underlead Aces - why that design??
#2
- Group: Advanced Members
- Posts: 4,155
- Joined: 2003-May-14
Posted 2012-May-28, 13:28
It doesn't "consistently" underlead aces, rather it does it sometimes, and more often than humans do.
As for why, you have to remember that it doesn't make opening lead decisions using human-like heuristics. What it does, on basically every card it plays on defense, is deal a bunch of hands that match the information it has available, which is the auction, dummy's cards if after first lead, and previously played tricks. Then it solves each of these possible hands to find the card(s) that work best on average over these possible hands. If it then thinks that underleading the ace will on average score better than leading the ace, or other cards, then it will go ahead and underlead the ace. Now if this works out badly on a particular hand, it could be because partner doesn't expect it (if human partnering GIB, you should be aware of this possibility), or because maybe its understanding of the auction is wrong because of holes/bugs in the bidding DB. You might post the hand in question if you think the bid descriptions are out of whack and made it perhaps consider underlead when it probably shouldn't have.
There are no commandments in the software saying "don't underlead aces", or "always underlead aces". The only command really is "pick the card that you think works best on average". If cards are tied, it tends to be random in the middle of the hand I believe, but on very first opening lead it will adhere to human lead conventions like top of sequence.
As for why, you have to remember that it doesn't make opening lead decisions using human-like heuristics. What it does, on basically every card it plays on defense, is deal a bunch of hands that match the information it has available, which is the auction, dummy's cards if after first lead, and previously played tricks. Then it solves each of these possible hands to find the card(s) that work best on average over these possible hands. If it then thinks that underleading the ace will on average score better than leading the ace, or other cards, then it will go ahead and underlead the ace. Now if this works out badly on a particular hand, it could be because partner doesn't expect it (if human partnering GIB, you should be aware of this possibility), or because maybe its understanding of the auction is wrong because of holes/bugs in the bidding DB. You might post the hand in question if you think the bid descriptions are out of whack and made it perhaps consider underlead when it probably shouldn't have.
There are no commandments in the software saying "don't underlead aces", or "always underlead aces". The only command really is "pick the card that you think works best on average". If cards are tied, it tends to be random in the middle of the hand I believe, but on very first opening lead it will adhere to human lead conventions like top of sequence.
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