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Rosenkranz double

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Rosenkranz double

The Rosenkranz double and Rosenkranz redouble are elements of a bridge bidding convention invented by Dr. George Rosenkranz, collectively known as the Rosenkranz double.[1] It is a double bid made by the advancer (partner of the intervenor) in an auction where opener, intervenor and responder have all bid different suits. It is used to describe the advancers top honor card holdings in the intervenors suit.

Original version

The conventions come into play when the auction has started with: (a) an opening bid by the opponents; (b) a direct overcall by partner at the one-level; and (c) a bid or negative double (i.e. not a ‘Pass’) by the opener’s partner (the responder). Three cases follow: (1) if responder made a bid below two of opener's suit, a ‘double’ by the advancer is a raise of the overcaller’s suit and promises a top honor; (2) likewise, if opener’s partner doubles the overcall, a ‘redouble’ by the advancer has the same meaning; but (3) if, instead, the advancer makes a raise to the two-level in overcaller’s suit, he denies possession of a top honor in that suit. A top honor is either the Ace, King or Queen.

Showing the top honor may allow the overcaller with a serrated holding to lead the suit safely; while denying the top honor (and thereby suggesting strength elsewhere) encourages the overcaller to lead a different suit.

Reverse Rosenkranz

Subsequent to creating the Rosenkranz double and redouble, Rosenkranz announced in a letter published in the ACBL's Bridge Bulletin[2] that he had adopted a proposal by Eddie Wold to switch the meaning of the two sequences, so that the advancer's immediate raise now showed the Ace, King or Queen honor, while the double (and redouble) denied it - a treatment known as "Reverse Rosenkranz". The term "Guildenstern" (a reference to Shakespeare's other courtier in the play Hamlet) is also used for these sequences in independent creation of "Reverse Rosenkranz".

The reasoning for the reverse treatment is that a better hand for the bid suit (by virtue of the additional honor strength) should raise the level of the auction to make things difficult for the opponents.


Munson, created by Kitty Munson Cooper, (or sometimes, "Tolerance Redoubles"[3]) in which the redouble shows shortness (one or two cards) including the ace or king. After a Munson redouble, the overcaller's spot-card lead in his overcalled suit is suit preference for the side suit to shift to.

The Rosencranz redouble is also used to indicate an honor doubleton in overcaller's suit.[4]

The Snapdragon convention is a double by advancer when three different suits have been shown by the other three players, and nobody has jumped. It shows length in the fourth (unbid) suit, and tolerance for partner's suit (10x or better).


External links

  • Rosenkranz Double
  • Snapdragon double

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