Negative Doubles
                          ----------------

My own notes (prior to 1998)
----------------------------

  Most popular variation
     After partner opens, and RHO overcalls a negative double shows the
     other two suits.  However, over 1min - 1maj a double guarantees the 
     other major and less so on the other minor.


  "Expert" variation
     After 1min - 1maj a double shows 4+ of the other major, saying 
     nothing about the other minor.  After 1C - 1D a double shows at 
     least 4-3 in the majors, and after 1H - 1S a double shows both 
     minors.


  A very different variation
     After 1min - 1maj a double DENIES the other 4 card major.
     Also after 1C - 1D a double DENIES a 4 card major.  


Notes from Marty Bergen's book (July 2002)
------------------------------------------

Notes from "Point Schmoints Series: Negative Doubles" by Marty Bergen, 
Magnus Books, Stamford, CT (2000).  Although Bergen doesn't list Losing 
Trick Count, I've included that in the notes.  Number like 17-6 means
that the bids needs at least 17 hcp and the example hands had 6 losers.


  Negative doubles
  ================
  * hands that do not have the strength or length to bid
  * essential for finding 4-4 fits
  * the suits shown by the double depends on which suits are unbid:
      -with one unbid major, double promises the unbid major
      -with two unbid majors, double promises at least one major
         except 1C - 1D - dbl shows at least 4-4 in the majors
      -with two unbid minors, double promises at least one minor  
  * Points needed for making a negative double depends on the
    level and overcall:
       one level  = 6 hcp
       two minor  = 8 hcp
       two major  = 9 hcp
       three and higher = 10 hcp
  * High negative doubles (4D and above) do not promise a four card
    major (or any other distribution, for that matter).

  Other notes:
  * 1C - 1D/1H - 1S shows five spades
  * Bergen recommends playing weak jump shifts in competition (~2-7 hcp)


  Opener's rebids after a negative double
  =======================================
  * with no other options opener can rebid in a three card major or in a 
     five card suit
  * jumps are inviting
  * double and triple jumps are highly inviting
  * reverse  
      1C followed by 2D: 17-6
      higher reverses: forcing to game
  * cuebid is forcing to game, nothing about distribution (not even support!)
  * 1NT minimum
  * 2NT 18-19 hcp, balanced or unbalanced
  * 3NT unbalanced with ~8 tricks

  Specific examples (he has a lot more listed)
  ============================================
  1C - 1D - dbl = at least 4-4 majors
     opener rebids
     1H  13-7, bad hearts  4-4 shape shown
     2H  14-7, good hearts 4-4 shape
     3H  16-6, 5-4 shape
     4H  14-5, 6-4 shape

  1H - 2C - dbl = four spades, denies three card support

  1x - 3y - dbl
     opener should "rarely introduce a three card suit at the three level"

  1x - 4C - dbl
     opener rebids
     4D   FORCING
     cue  promises void, slam forcing
     4N   ace asking

  1x - 4D/4H/4S/5m - dbl = no longer promises a four card major


  Other treatments
  ================
  * 1C - 1D - dbl = could be 4-3 in the majors (poor four, good three)  
  * 1m - 1H - 1S = just four spades
  * Preempt after a preempt
  * 1x - 4H/S - 4NT = two suited takeout (not including spades  


  Bergen's own ideas
  ==================
  * THRUMP doubles (THRee no trUMP doubles)
     a double of a 3D/3H/3S overcall denies a stopper, biddable five
     card major and three card support for opener's major.  The double
     asks opener to bid 3NT with a stopper; it doesn't guarantee a four
     card major.  It could be slam inviting.
  
  * THRUMP 3S
     1x   - 3C - dbl - p;
     3D/H - p - 3S
     After a double or 3C AND opener's rebid of 3D or 3H, responder's
     3S asks opener to bid 3NT with a club stopper.

  * 1x - 1H/S - 3H/S = Jump Cue
     denies other major, shows stopper, usually a transfer to 3NT 
     to get a lead up to Qx or Jxx.

  * No unbid majors 
     double denies 12 hcp
     1H - 1S/2S - dbl  
     1S - 2H    - dbl