# alias: NegativeDouble
# button-text: Negative Double
# gib-works: true
# bba-works: true
# auction-filter: 1[CDHS] (1[DHS]|2[CDH]) X
# convention-card-ns: 21GF-DEFAULT
# convention-card-ew: 21GF-GIB
# curate: kind=bidding

/*@chat
--- Negative Double
After x (y), X is a Negative Double.  It's for takeout. At the 1-level
it promises 4-Cards in each unbid major. At higher levels you need a backup
plan if partner doesn't have your major -- maybe a tolerance for opener's suit.
https://www.larryco.com/bridge-articles/negative-doubles
4NT is Roman Keycard Blackwood (1430) with a trump suit agreed, or quantitative (inviting 6NT) in a notrump auction. Keycard responses:
  • 5!C = 1 or 4 keycards
  • 5!D = 0 or 3
  • 5!H = 2 without the trump queen
  • 5!S = 2 with the trump queen
@chat*/

# Negative Double

dealer south
produce 10000

#include "script/Predict-Opening-1-Bid"

# Predict West's overcall
sW = spades(west)
hW = hearts(west)
dW = diamonds(west)
cW = clubs(west)
wS = sW>=hW and sW>=dW and sW>=cW
wH = not wS and hW>=dW and hW>=cW
wD = not (wS or wH) and (dW>=cW or cW==3)
wC = not (wS or wH or wD)

# South Opens
sOpens = (oS or oH or oD or oC) and hcp(south)>11

# West overcalls
wOvercalls = (wD or wH or wS or wC) and shape(west,any 6xxx+any 5xxx-any 65xx -any 55xx)
wP1 = hcp(west)>7
wP2 = hcp(west)>10

p1 = hcp(north)>5
p2 = hcp(north)>9
p3 = hcp(north)>11

# North doubles
nM = shape(north,44xx+45xx+54xx)
nH = shape(north,x4xx)
nS = shape(north,4xxx)
x1 = oC and wD         ? nM and p1 : 0
f1 = oC and wD         ? (nH or nS) and p1 : 0 // What if Partner bids the wrong M?
x2 = oC and wH         ? nS and p1 : 0
x3 = oC and wS         ? nH and p1 : 0
x4 = oD and wH         ? nS and p1 : 0
x5 = oD and wS         ? nH and p1 : 0
x6 = oD and wC         ? nM and p2 : 0
f2 = oD and wC         ? (nH or nS) and p2 : 0 // What if Partner bids the wrong M?
x7 = oH and (wC or wD) ? nS and p2 : 0
x8 = oS and (wC or wD) ? nH and p2 : 0

nDoubles = (((x1 or x2 or f1) and p1) or ((x3 or x4 or x5) and p2) or ((x6 or f2 or x7 or x8) and p3))

sOpens and wOvercalls and nDoubles

action
#printoneline,
average "1C (1D) H&S " 100 * x1,
average "1C (1D) H/S " 100 * f1,
average "1C (1H) S   " 100 * x2,
average "1C (1S) H   " 100 * x3,
average "1D (1H) S   " 100 * x4,
average "1D (1S) H   " 100 * x5,
average "1D (2C) H&S " 100 * x6,
average "1D (2C) H/S " 100 * f2,
average "1H (2C/D) S " 100 * x7,
average "1S (2C/D) H " 100 * x8,