[BLML] The Monty Hall trap

Nigel Guthrie nigelguthrie at yahoo.co.uk
Tue Dec 14 10:23:02 CET 2010

[Eric Landau]
That's not, however, the way things work in the ACBL, where even this

common and well-known "baby psych", once perpetrated within a
partnership, immediately morphs into an illegal implicit agreement,
which, as such, may not be repeated.

[Jerry Fusselman]
Why do you say illegal?  It could be described as a conventional
defence to a conventional call, perfectly legal under even the GCC.

Jerry has pin-pointed a difficulty.

There are many tactical situations where some players deviate from system. For 
- 3rd in hand openers.
- 1H (X) bid.
- 1N over-calls.
- Interfering with opponent's strong artificial 1C/2C
- Passing partner's pass/convert response in the the wrong suit.
- Spurious trial/cue/exclusion bids.
- "Game-forcing" calls on tram-tickets.  

The problem is that different partnerships have different favourite situations 
and hand-types; and some never "psych" at all.

Regular "psychs" in a regular partnership aren't true psychs. Even if only 
occasionally used, they are probabilistic conventions. 

The disclosure problem is that: 
- Partnerships convince themselves that these are true psychs; hence not 
- Partnerships defend their personal idiosyncratic "psyching" propensities as 
"general knowledge".
- Partnerships feel that they *cannot disclose* these understandings because the 
agreements would be illegal. For instance, there may be strength requirements 
for opening bids; or "Random" bid agreements may be banned; or non-symmetric 
methods may be banned (some partnerships comprise a straight man and a 

Manifestly, undisclosed, such agreements are illegal. 

This problem would be mitigated if system-restrictions were scrapped, because 
partnerships would then be more ready to admit to such understandings.

More information about the Blml mailing list