[mr1303]

Just had a hand that I'm almost certain I've played previously. It was played in the Acol club this evening.

Could this happen?

[han]

Of course it can. Perhaps a more important question is, did you play the hand better than the first time?

[frank0]

Nice comment by ham lol.

Let me answer the unimportant question. First I think it's better to make sure whether one of the hand is pre-dealt. Assume not, then the probability of having two exactly the same hand is not as bad as you thought.

I'm assuming you mean you hold exactly the same 13 cards twice(but opp can have different cards).

Total number of possible hands N=C(52,13)=52!/13!39!
Total number of hands you play in your life time=m

First we calculate the probability that you haven't played exactly the same hand twice after you've played m hands.
m=1,P=1
m=2,P=(N-1)/N
m=3,P=(N-1)/N * (N-2)/N ->because your third hand has chance to be the same as your first hand and your second hand
......
after m hands
P= N*(N-1)*...(N-m+1)/N^m = N!/(N^m*(N-m)!)
apply stirling approximation http://en.wikipedia....s_approximation
lnP~-m+(N-m+0.5)*ln(N/(N-m))

The probability that you hold the same hand twice in your life is 1-P

Define people who addict in bridge is those who play more than 50 hands/week(2 club games per week is more than that).
A person who addict in bridge for 50 years in his/her life has played at least 130000 hands, in that case
1-P~0.013
which means in average 1 out of 77 addicting players have the experience of having same hand twice in their life but they cannot remember it.

For those professional players, I estimate m=1000000 and I get 1-P~0.545, about half of them have the experience of having exactly same hand twice in their life!!

Back to the top, if you mean the whole hands(in 4 players) is exactly the same.
We just need to let N=C(52,13)*C(39,13)*C(26,13)*C(13,13) and I leave it to you.

[Free]

frank0, on 2011-October-23, 03:27, said:

For those professional players, I estimate m=1000000 and I get 1-P~0.545, about half of them have the experience of having exactly same hand twice in their life!!

They'll have to play a hell of a lot of games. 8 hours a day, each day throughout the year, 5 minutes a deal, takes 28.5 years. 6 minutes a deal take this to 34.25 years. The more normal 7 minutes requires almost 40 years. And that's playing non-stop, and not considering the fact that most professionals also play a lot of the same deals. I don't have any close friends that are bridge professionals, but I'm sure they like to do something else than "wake up, eat, play some hands, eat, play some hands, eat, play some hands, go to sleep" each and every day for 40 years . They probably also spend time analyzing hands, reading books, work on their system, writing on the forums,... plus they also need to travel from time to time.

That being said, it's definitely possible to have the exact same hand twice, but unlike Han is suggesting in a way, having the same hand and the same dummy, or even playing the exact same deal is extremely unlikely.

[whereagles]

Sure it can. I get balanced 12-14s all the time.

[EricK]

About 10 years ago or so, I remember playing the same deal at the local club as the previous week (if I recall it had 8 ♥ to the J). Since this was about half way through the evening, and nobody else seems to have noticed, I didn't bother pointing it out. The first week the opps had the long hearts, the second week I had them. I think I made more of the opportunity than they had done

[Free]

EricK, on 2011-October-23, 15:52, said:

About 10 years ago or so, I remember playing the same deal at the local club as the previous week (if I recall it had 8 ♥ to the J). Since this was about half way through the evening, and nobody else seems to have noticed, I didn't bother pointing it out. The first week the opps had the long hearts, the second week I had them. I think I made more of the opportunity than they had done

Ah yes, I had that too, already forgot about it! I didn't even notice it myself because I held other cards than the week before...

[FrancesHinden]

mr1303, on 2011-October-22, 16:13, said:

Just had a hand that I'm almost certain I've played previously. It was played in the Acol club this evening.

Could this happen?

I've seen this happen at another club, but where a board somehow got missed out on getting dealt. Obviously more likely with hand-dealt boards, but it can still happen. Human error gets everywhere!

[Fluffy]

years ago on one of the crowdy simultaneos tournaments over the world, they somehow decided to pick boards that had been played in a european championship some years ago. Obviously my dad remembered most of the boards... but only when they were done or he was declarer, during the bidding when you hold cards of an opponent of yours you don't remember anything.

[gwnn]

Does anyone have statistics on how many boards there are if you treat all x's as equal? What would the probability be of getting two of those in a lifetime?

[Flameous]

Also if we consider small spots equal (you wouldn't probably remember them all right anyways) chance goes up a whole lot to play 2 "same" hands.

However most of the times I hear this kind of things, it's due to hands not being shuffled. I actually heard a story that one set of cards had lied unused for over 10 years and then they were used in some tournament. One guy actually remembered he had played those boards already

[blackshoe]

Someone, I think it was Al Roth, once called the director because, he said, "we've played this board before". His 3 opponents demurred, at which point Roth named the location of all 52 cards.

[Cyberyeti]

EricK, on 2011-October-23, 15:52, said:

About 10 years ago or so, I remember playing the same deal at the local club as the previous week (if I recall it had 8 ♥ to the J). Since this was about half way through the evening, and nobody else seems to have noticed, I didn't bother pointing it out. The first week the opps had the long hearts, the second week I had them. I think I made more of the opportunity than they had done

We had a case where the same wild board turned up 3 times in successive weeks at our club. The board was so strange (I was in 3 different seats), that I didn't recognise it till the third time it appeared when dummy hit, and was able to play it as the auction determined who was getting a good score (whether you go for 1400 or 1700 doesn't matter much on a game board). It was one of those boards where the first player had 8 to the 10 and out, and the second player had 8 to the AKJ and some stuff, so the first 2 bids varied wildly and the auction was very different on the 3 occasions.

[Fluffy]

from my mother´s memories on the local club, it was not that uncommon for 2 pairs of old people to play the same hand twice during the same round, and score twice with different results and never noticing that something had gone wrong.

[EricK]

Last week our club took part in a simultaneous pairs for Charity, so the hands were predealt. This week, I picked up the curtain card for Board 25 and thought "I think I've had this hand last week". The hand was the same, but the cards themselves were different i.e. it was a new pack of cards but the bridge hand was the same. Indeed the whole hand was exactly the same as the board 25 from the previous week.

I have no idea how this could have happened (barring deliberate foul play). i.e. Why should someone, this week, set up the hand to be exactly the same as last week with a new pack of cards? Where would they find the time without anybody else noticing?

Nobody else at the table seemed to have noticed, so I bid it the same way as I did the previous week (making the same substandard vulnerable 2 level overcall!) - largely as an experiment to see if my partner's reactions were the same as last week (they were - the same facial expressions and contortions during the bidding, and the same misbids).

This was very near the end of the evening and after the hand - I went to the director's table and asked if they'd played it. They hadn't yet, but were due to play it in the last round. So I said nothing and went back at the end and asked them if they'd noticed anything unusual. They hadn't. When I pointed out it was a repeat of last week, director's partner said her hand looked a little familiar (she had 0 points, and a 0463 distribution, so it was a bit unusual), but it couldn't have been because the pack of cards was new.

I can't say that nobody else at the club noticed, but certainly nobody else had mentioned it to the director.

[Hanoi5]

Fluffy, on 2011-October-30, 04:28, said:

from my mother´s memories on the local club, it was not that uncommon for 2 pairs of old people to play the same hand twice during the same round, and score twice with different results and never noticing that something had gone wrong.

I've seen the same several times in Venezuela.

EricK said:

I have no idea how this could have happened (barring deliberate foul play). i.e. Why should someone, this week, set up the hand to be exactly the same as last week with a new pack of cards? Where would they find the time without anybody else noticing?

Are the boards dealt by a machine? Pre-dealt by a computer? I have set up boards when I direct (and seen others do it, too) but it's not usual.

[EricK]

Hanoi5, on 2011-November-23, 08:12, said:

Are the boards dealt by a machine? Pre-dealt by a computer? I have set up boards when I direct (and seen others do it, too) but it's not usual.

On a normal club night, the boards are given out to the people who arrive early, and they shuffle and deal them. For the simultaneous pairs, my understanding is that the travellers were provided with the hands printed on them, and someone who was not playing set up all the boards based on these.