[frank0]

I just tried to create an example deal of "maximal double" for bidding practice, using BBO hand generator.

Here is my setting
South, 5♠, 1~4 in other 3 suits, 15~19HCP
West, no restriction
North, 3♠, 2~4 in other 3 suits, 8~9HCP
East, 6+♥ and 10+HCP

Trying to make the auction become 1♠-P-2♠-3♥-X

This is not a problem. However, I just noticed under this condition I cannot generate any hand that South does not have ♥K and ♥J(I've redealed about 50 times). Is there any flaw with the random hand generator?

[BunnyGo]

Probably just the law of small numbers. It took me one simulation to not have this...

[barmar]

I just tried it and I got lots of hands where South doesn't have those cards.

[frank0]

BunnyGo, on 2012-February-15, 21:30, said:

Probably just the law of small numbers. It took me one simulation to not have this...

It may be, but 50 is not very small though...

Hm, I just log in again and notice this is not the problem of this specific condition. The problem is it remembers part of South's hand after you do the editing.

Try this,
1. generate a random deal w/o restriction.
2. Switching 2 South's card with 2 East's card.
3. Keep clicking redeal, one of South/East will always have the 2 cards it gains from East/South.

[barmar]

I dealt a couple of dozen hands, and hardly had any where South had those two cards. It frequently had a small singleton.

[BunnyGo]

frank0, on 2012-February-15, 22:02, said:

It may be, but 50 is not very small though...

Hm, I just log in again and notice this is not the problem of this specific condition. The problem is it remembers part of South's hand after you do the editing.

Try this,
1. generate a random deal w/o restriction.
2. Switching 2 South's card with 2 East's card.
3. Keep clicking redeal, one of South/East will always have the 2 cards it gains from East/South.

This is definitely the law of small numbers. Remember Frank that it's not just this one pattern that you were "looking for", rather it was thousands of patterns your mind could have picked out. Any specific one of these occurring is certainly rare, but humans are good at finding patterns in randomness.

[billw55]

Assuming frank's report is fully accurate, this must be a flaw in the dealer as running on his machine. 50 deals with two specific cards in the same hand is far, far too many to reasonably be attributed to chance.

[fred]

The hand editor in the web-client allows you to assign specific cards to specific players and then generate the rest of the deal randomly (with or without constraints).

I imagine that is what happened here. Frank (unintentionally from the sound of it) assigned the King and Jack of hearts to South. I suppose it is also possible that a bug was responsible for assigning these cards to South, but if so I strongly suspect it is a bug in the web-client itself (as opposed to a bug in the hand generator).

Fred Gitelman
Bridge Base Inc.
www.bridgebase.com

[barmar]

I was doing my test using the web client.

[frank0]

fred, on 2012-February-16, 09:06, said:

The hand editor in the web-client allows you to assign specific cards to specific players and then generate the rest of the deal randomly (with or without constraints).

I think it's the reason.