[barmar]

VixTD, on 2013-June-19, 11:18, said:

I think you're being too cautious in allowing this score to stand. I don't think you need to prove intent, or demonstrate that this is a common occurrence. The choice of action itself is sufficient. I would rule the same way in all the situations given, and perhaps take further action about the advertent or inadvertent signalling. This is not a matter of penalising beginners for making mistakes. I do wonder if it's an overreaction to the backlash against the "rule of coincidence".

Isn't that the very definition of the rule of coincidence? You don't have evidence of intent, UI, or CPU. You're just treating it as illegal because both players took unusual actions on the same hand, and they happened to fit together.

[PhilKing]

barmar, on 2013-June-20, 09:17, said:

Isn't that the very definition of the rule of coincidence? You don't have evidence of intent, UI, or CPU. You're just treating it as illegal because both players took unusual actions on the same hand, and they happened to fit together.

Does this rule exist?

[blackshoe]

There are several forms of "rule of coincidence", from several different disciplines. I think what Barry's talking about is the notion that "if two partners did unusual things that happened to compensate for each other, there was automatically an infraction". I'm quoting Steve Willner here, from a post on rec.games.bridge last March 31. He went on to say "That rule was never in effect, at least officially, though I suppose some incompetent Directors probably enforced it".

Steve gave another form of the rule "A weaker version of RoC is as a rule of evidence. If there is a possible infraction, decisions are made on "balance of evidence," i.e., which possible set of facts is more likely, given all the evidence available. A "Rule of Coincidence" is one possible form of evidence.

Suppose a player opens 1NT, announced as 15-17, with 14 HCP, and all pass. Opponents misdefend, expecting opener to have a 15th point, and claim they were misinformed. The Director will seek evidence, in particular how often responder has seen 14 HCP openings from partner. If opener and responder are a first time partnership, there's unlikely to be an infraction. Opener is entitled to deviate from his announced agreements. If instead responder knows that opener often bids 1NT with 14 points, failing to tell the opponents that is MI: the true agreement is not 15-17 but 14-whatever. If the Director sees that responder has passed with 10 or 11 HCP, he is very likely to rule that way unless responder has a very convincing alternative explanation for the pass. There might be such an alternative explanation -- perhaps RHO was fingering the double card -- but absent one, the probabilities favor the true 1NT range starting at 14 or even lower.

Using the RoC in this way -- one form of evidence out of many -- is good directing and has always been in effect."

[nige1]

IMO, rule of coincidence is just a short and intuitive way of arguing balance of (Bayesian) probability (Thus it can be the basis of a legal ruling and is a topic on which Steve Willner is expert).

[barmar]

PhilKing, on 2013-June-20, 16:43, said:

Does this rule exist?

No, that's the point.

[PhilKing]

nige1, on 2013-June-20, 21:17, said:

IMO, rule of coincidence is just a short and intuitive way of arguing balance of (Bayesian) probability (Thus it can be the basis of a legal ruling and is a topic on which Steve Willner is expert).

I think this is utterly wrong.

It's 100% percent certain that dubious pairs will have boards where the actions of player B suggests that their knowledge of the hand held by player A was other than stated, but entirely honest pairs will have these boards as well, but less frequently.

As long as the former pairs are rare, the number of false positives will exceed the real ones, so a ruling with no other evidence would be shocking.

[VixTD]

The way I was taught to check for fielding (going back to my EBU club directors' training 25 years ago) was to ask: "Has offender's partner taken unexplained action that could protect the partnership from the effects of the psyche?"

(I don't think that phrase is written in any official guidelines, it's just what I remember the late Ian Spoors saying on the course.)

If partner has opened 1♠, or responded 1♠ after 1♣ (X), then failing to raise spades when holding 3+ and suitable values is indicative of not believing that partner has the spades they have shown.

In the original problem, holding ♠A ♥K73 ♦QJ764 ♣AJ94 after the auction P - 1♦; 1♠ - 2♣; 2NT - P

the only things that could persuade me this is not a case of fielding are: (1) If West could come up with a convincing explanation for failing to raise to game. (2) If I thought that, if East didn't have their bid, they were at least as likely to be overstrength as understrength.

For (1) West might try to argue that partner has passed so can't have much, the hands could misfit quite badly, they desperately need a swing, etc., but I don't think it will work. I just don't believe (2) applies, and wouldn't apply even if East hadn't originally passed. A beginner might bid 2NT with 13+ because they have a balanced hand and so they have to bid no trumps, not realising that they have just made a bid partner can pass, but below-average players won't do this. They might bid no trumps on a weak hand in an attempt to get out of a misfit, but not knowing how.

I can understand the argument that some of you are putting forward that there needs to be more evidence than just coincidence, and that what the TD should do here is sort out any implicit agreements EW might have here and make sure they disclose them in future, or rule under UI if the offending bid were slow or there were some other telling mannerism. I think there's sufficient likelihood that East was weaker than shown and that West's action could have allowed for this.

I'm willing to be persuaded otherwise.

[blackshoe]

Are you ruling red psych or amber?

[VixTD]

blackshoe, on 2013-June-24, 08:27, said:

Are you ruling red psych or amber?

Red misbid.

[blackshoe]

Why red? It seems to me that it's at best amber.

[VixTD]

If partner has their bid (10-12 pts) you clearly want to be in game. This is a clear case of fielding. If West had taken a conservative action where they might well have been a little more bold I would agree with you (say if they had ♠A ♥K73 ♦Q8764 ♣AJ64).

[blackshoe]

Hm. Maybe. Although I daresay if it was all that clear I wouldn't have been asking questions.