SAYC_2_1_openings.rb

require 'bridge'
SAYC_2_1.define do
  # opening: true implies requirement that history contains only pass bids
  convention :strong_2_club do
    opening true
    long_points minimum: 22
    balanced true
    bid level: 2, strain: Bridge::Strain::Club
  end

  convention :one_notrump_opening, tags: :notrump_opening do
    opening true
    high_card_points 15..17
    balanced true
    bid level: 1, strain: Bridge::Strain::NoTrump
  end

  convention :two_notrump_opening, tags: :notrump_opening do
    opening true
    high_card_points 20..21
    balanced true
    bid level: 2, strain: Bridge::Strain::NoTrump
  end

  convention :three_notrump_opening, tags: :notrump_opening do
    opening true
    high_card_points 25..27
    balanced true
    bid level: 3, strain: Bridge::Strain::NoTrump
  end

  convention :major_opening do
    opening true
    length suit: Bridge::Strain.majors, minimum: 5

    seat 1..4 do
      long_points minimum: 13
    end

    seat 3..4 do
      long_points minimum: 11
    end

    seat 4 do
      only_if do |hand, _history| # rule of 15
        hand.length(Bridge::Strain::Spades) + hand.high_card_points >= 15
      end
    end

    bid do |hand, _history|
      strain = hand.length(Bridge::Strain::Heart) > hand.length(Bridge::Strain::Spade) ? Bridge::Strain::Heart : Bridge::Strain::Strain
      bid! level: 1, strain: strain
    end
  end

  convention :minor_opening do
    opening true
    length suit: Bridge::Strain.minors, minimum: 3

    seat 1..4 do
      long_points minimum: 13
    end

    seat 3..4 do
      long_points minimum: 11
    end

    seat 4 do
      only_if do |hand, _history| # rule of 15
        hand.length(Strain::Spades) + hand.high_card_points >= 15
      end
    end

    bid do |hand, _history|
      strain = if hand.length(Bridge::Strain::Diamond) == hand.length(Bridge::Strain::Club) && hand.length(Bridge::Strain::Diamond) == 3
                 Bridge::Strain::Club
               elsif hand.length(Bridge::Strain::Diamond) >= hand.length(Bridge::Strain::Club)
                 Bridge::Strain::Diamond
               else
                 Bridge::Strain::Club
               end

      bid! level: 1, strain: strain
    end
  end

  convention :preempt_opening do
    opening true
    long_points 7..12

    only_if do |hand, _history|
      (Bridge::Strain::Suits - Bridge::Strain::Club).any? do |strain|
        hand.length(strain) >= 6 && hand.strong?(strain)
      end || (hand.length(Bridge::Strain::Club) >= 7 && hand.strong?(Bridge::Strain::Club))
    end

    bid do |hand, _history|
      strain = hand.longest_suit # TODO: could be 6/6 or 7/6 and only one strong
      bid! level: (hand.length(strain) - 4), strain: strain
    end
  end
end

Thanks so much for including me on this gist1

I had some more thoughts (and released them...) while meditating:

More problem domain nomenclature; I'm not sure what of this you know, so here's a brain dump of my understandings: bids are calls and (re)doubles are calls and passes are calls. (Re)doubles and passes are not bids. Opener is the first to make a bid call; Responder is his partner. Overcaller is the first to make a bid call (I think, not a double), and Advancer is his partner. The system (Standard American) describes natural bid calls, pass calls, and doubles (for penalty). Conventions are codified in http://web2.acbl.org/documentLibrary/play/ConventionCard.pdf which contains a great deal more problem domain nomenclature. Standard American Yellow Card is the Standard American system with the Yellow Card set of conventions adopted from the convention card, codified here: http://web2.acbl.org/documentlibrary/play/SP3%20(bk)%20single%20pages.pdf . Aside: the big difference between the system "Standard American" and 2-over-1 which Zack's club plays is the point range of a natural non-jump bid of two in a new suit by responder: in Standard American, it is 10-18 (I think) points long; in 2-over-1 it is 12-18 (I think) points long.

Also, it occurred to me (again while meditating) that a format similar to this one is a potential format for the _history argument, inspired by section 3.5 at http://www.tistis.nl/pbn/pbn_v21.txt :

1D 1S 3H 4S
4NT X Pass Pass
5C X 5H X
Pass Pass Pass

That is, in CS theory terms, valid auctions and completed auctions are themselves (finite) languages drawn from the alphabet (sigma) of calls, where the machine recognizing the latter language not only verifies that the sentence (sequence of calls) obeys the bidding rules (as with the former language) but also requiring that it end in "[Call] Pass Pass Pass". I'm not sure if it's a helpful language, because the level of abstraction may be wrong: perhaps you'd like _history to have some other, perhaps OO, richer structure than "sequence of calls", since you're not trying simply to recognize valid sentences, but rather test incomplete auctions for utility, right? Still, just figured I'd share my meditation noodling.