Sunday, July 25, 2010

All the compound squeezes

I've spent a lot of time enumerating and trying to name various squeezes. Here's a quick summary of all the compound squeezes (pure, without trumps), just based on naming conventions. I think a name should contain enough information to specify the whole squeeze. Concise names should do little more, but as squeezes get more hairy it can be nice to have some redundancy. Here, I'm trying to be concise. This might be (i.e. probably is) only useful to me.

1. There are type-R (2 double threats opposite a lone basic menace), type-L (1 double threat opposite a basic menace and an adjacent double threat), and Alternate Threat (like type-L, except the adjacent double threat suit also has an alternate threat in the other hand). In both cases, one hand has only one menace, designated the "lone" menace.

2. Type-R and Type-L can be restricted or unrestricted. Unrestricted basically means that the lone menace is recessed -- this makes room for idle cards opposite so you can run the free suit.

3. The standard "basic" menace (i.e. guarded by one opponent who is under the menace) is just a 1 card menace. If an entry is required, it might become "2-card", i.e. Ax/x. Recessing is often required to make room in the other hand, this can make a 1-card a 2-card-non-communicating (2CNC, Ax/-), or a 2-card a "recessed" (AKx/x). If an entry is required to the opposite hand, it can become "blocked" (xx/A), or "twin-entry" (Axx/Kx).

4. The standard double menace in a pure compound is a 2-card (Ax/x). This can be recessed to make room opposite, or twin-entry to add an entry opposite. A 3-card might also be necessary (AKx/xx, where both entries are important -- contrast with "recessed"). In alternate-threat squeezes, either a 2C or a 3C might need an alternate threat: 2-card-alt (Ax/xx) or 3-card-alt (AKx/xxx).

There are 2 double menaces in a compound squeeze. In a type-L, one is "adjacent" to the basic menace and the other is "opposite". In a type-R, both are opposite. Often one of them needs some extra feature, but it doesn't matter which has it (since it's symmetrical).

5. The free suit is normally 2 winners with the lone menace. In an unrestricted squeeze, they both might be opposite; these positions are called "adjoints". Sometimes, a late entry is used in the free suit -- these have "balanced" free suits, such as AK/xx (Ax/Kx also fine). Sometimes the penultimate free winner needs to be in the opposite hand, a "blocked free suit" (though again Ax/Kx would work fine).

In my naming convention, the type (R/L/alternate) describes the basic layout of the menaces and minimum necessary (but not sufficient) entries (see row I, II, and II-C). "Unrestricted" says something about the lone menace: that it has an extra winner without (necessarily) a corresponding link opposite. But, each basic family potentially has some additional entry requirements that are satisfied by upgrading one or more standard menaces. The type of upgrade and the upgraded menace(s) constitutes the rest of the name.   Often specifying which menace is upgraded is redundant, but still helpful.

In hand diagrams, spades is always basic and in North (guarded only in West), clubs is always free, and the red suits are always double menaces, guarded by both opponents (diamonds is always opposite, in South; hearts might be in either hand). An 'o' designates an idle card.

In the outline, every line using arabic numerals corresponds to a distinct compound, where as long as East can't stop spades, declarer can take the rest (might also require that the hand with CA is on lead).

I. Type-R (implies at least x/x/x/AK opposite -/Ax/Ax/o)

    A.  Unrestricted (implies spades is 2CNC or recessed: Ax/- or AKx/x)
  • requires a reentry to the basic hand, could be in basic suit (B) or one of the double menaces opposite (O). Free suit (F) not possible since it's cashed first.
          1.  Type-R Unrestricted Recessed basic
               AKx/x/x/AK opp x/Ax/Ax/oo

          2.  Type-R Unrestricted Twin-entry opposite
               Ax/Kx/x/AK opp -/Axx/Ax/oo
  • both of the above could be "adjoint", with the free winners in the other hand.
  • If the free suit is blocked, play is harder but nothing extra needed.
   B. Restricted
  • requires a reentry to the basic hand, could be in B, O, or F:
          3.  Type-R Restricted Two-card basic
               Ax/x/x/AK opp x/Ax/Ax/o

          4.  Type-R Restricted Twin-entry opposite
               x/Kx/x/AK opp -/Axx/Ax/o

          5.  Type-R Restricted Balance free suit (implies 2CNC basic)
               Ax/x/x/AK opp -/Ax/Ax/xx

II. Type-L (implies at least x/Ax/x/o opposite -/x/Ax/AK)

   A. Unrestricted (implies diamonds is recessed, AKx/x)

          6. Type-L Unrestricted (already fully specified)
              x/Ax/x/oo opp -/x/AKx/AK
  • has an adjoint with free winners in the other hand.
  • If the free suit is blocked, requires a reentry to the long free suit winner (3 possibilities if you include xx/AKQx as a possible double menace.)
   B. Restricted (implies diamonds is *not* recessed)
  • Requires a Spade/Heart reentry to the free suit after cashing HA, plus a late Spade/Diamond entry to give force to the basic menace (and now entry-less heart menace). All 4 combos ([S|H]-[S|D]) work:
          RFL squeezes:
          7. Type-L Restricted Twin-entry basic (both entries in spades)
              Axx/Ax/x/o opp Kx/x/Ax/AK

          8. Type-L Restricted Two-card basic, Twin entry adjacent
              Ax/Axx/x/o opp x/Kx/Ax/AK

          B1-Twin-entry squeezes:
          9.  Type-L Restricted Blocked basic, Twin entry opposite
               xx/Ax/Kx/o opp A/x/Axx/AK

         10. Type-L Restricted Twin entries adjacent and opposite
               x/Axx/Kx/o opp -/Kx/Axx/AK

   C. Alternate threat (implies at least Ax/Ax/x/o opp -/xx/Ax/AK)
  • SA is in the way when West unguards diamonds, need an entry to clear it while still retaining a heart winner (the SA itself is required to make room for the alternate threat). This entry can be in any suit (but if in the free suit, requires a reentry to South):
          11. Type-L Alternate Recessed basic
                AKx/Ax/x/o opp x/xx/Ax/AK

          12. Type-L Alternate 3-card-alt adjacent
                Ax/AKx/x/o opp -/xxx/Ax/AK

          13. Type-L Alternate Twin-entry opposite
                Ax/Ax/Kx/o opp -/xx/Axx/AK

          14. Type-L Alternate 3-card opp w/blocked free suit
                Ax/Ax/xx/A opp -/xx/AKx/KQ
  • In 14, the free suit blockage is essential.  In 11-13, there are some blocked free suit variants not shown.

To recap:

[Note that in restricted squeezes, the common pattern is to cash one free winner, potentially need to do some stuff ending in the other hand, and then need a reentry to the free suit. I strive to only use "reentry" to refer to getting back to the free suit.]

Type-R unrestricted needs a reentry: basic (1) or opposite (2). Adjoints possible.
Type-R restricted needs a reentry: basic (3), opposite (4), or free (5).
Type-L unrestricted needs nothing more (6). Adjoint possible.
Type-L restricted can be an RFL needing a spade (L) entry plus a reentry in spades (7) or hearts (8); or it can have a twin-entry opposite + reentry in spades (9) or hearts (10).
Type-L alternate-threat (implicitly restricted) can have an entry to the basic hand in any suit: 11-14.

I believe that's all of the pure compounds: 14 distinct positions, plus 3 adjoints (plus maybe 2 or 3 variants on a type-L unrestricted w/blocked free suit, and some alternate threat blocked free suit variants).  In most cases, the free suit being blocked is not a big deal, I don't treat those as separate positions.

1 comment:

  1. had a pseudo compound against the robots just a few days ago.


    1N-2C-2D-3N. The computer loves passive leads, so if you get to 3N without showing your suit, they often lead it. Sure enough, they led a heart, which turned out to be a singleton (!) and east played the queen. Two diamond finesses won. Now if the red suits weren't blocked there would be a legitimate compound squeeze. I guess you'd call it type-L unrestricted, although I'm not implying I studied this post :) In practice, the machine failed to find proper compound squeeze
    defense and unguarded clubs instead of spades, leaving me with a working type R.