Muiderberg convention

Muiderberg is a bidding convention in the card game bridge. It is a two-level preemptive opening based on a two-suiter with precisely a five-card major and a minor suit (four-card or longer). In Muiderberg the 2♥ opening denotes five hearts and an unknown minor suit, whilst 2♠ denotes five spades and an unknown minor suit. The convention is also known as the Dutch Two, Lucas Two or Woo Two (mainly UK) opening.[1] The convention is named after the Dutch village Muiderberg, the residence of the designers of the convention - Onno Janssens and Willem Boegem.[2]

Responses

The partner of the Muiderberg opener can take the following actions:

  • pass (with tolerance for the opened suit)
  • bid 3♣ (a pass-or-correct bid)
  • bid 3♦ to invite for game in the major suit
  • bid 2♠ (over 2♥) as a contract improvement (opener is allowed to raise with a suitable hand)
  • bid 3♥/♠ (opener's suit) as a preemptive raise
  • bid 3♠/♥ (other major) which is non-forcing but invitational
  • ask for the minor suit using a 2NT relay bid with a strong hand.

The 2NT response is often defined as forcing to game, for example in Biedermeijer and AcolPlus. In particular, with a strong hand with a good suit of its own or with support for partner's opened suit, responder must bid 2NT first, as there is no other way to establish a force. The Muiderberg opener can respond in several ways to the 2NT answer:

  • bid 3♣ with a minimum and clubs / with a four clubs
  • bid 3♦ with a minimum and diamonds / with a four diamonds
  • bid 3♥ with a maximum and clubs / with a five or more clubs
  • bid 3♠ with a maximum and diamonds / with a five or more diamonds
  • bid 3NT with 4-4 in both minors
  • bid 4♣/♦ with a 6+ cards in the bid suit

Both approaches (2NT forcing to game or forcing for one round only) are equally popular.

In competition, 3♣ is natural (opener is expected to pass) while 2NT asks for opener's minor suit and is not necessarily strong. Further, 4♣/♦ are defined as fit-bids in competition.

Variants

Partnerships may choose to play Muiderberg Twos (or the variants below) as: (a) at least 5-4 shape, (b) at least 5-5 shape, or (c) at least 5-4 when non-vulnerable but at least 5-5 when vulnerable, for added safety. Statistically, 5-4 hands are about four times as common as 5-5.

A variant known as Lucas Twos allow for five cards or more in the bid suit (diamonds, hearts or spades) and four cards or more in a second suit which can be any of the remaining three suits. Particularly in the UK, the term Lucas Two is often used to describe what is actually a Muiderberg Two, where the second suit has to be a minor; this makes it safer for responder to explore for a second-suit fit if short in opener's longest suit.

A difficulty with Muiderberg and Lucas Twos is that it is no longer possible to make a Weak Two bid with a single-suited major. These hands may instead be bid using the Multi 2 diamonds convention.

Another variant, called Antispades Twos, provides for either a two-suited hand containing at least nine cards in the two suits with four or more cards in the bid suit — clubs, diamonds or hearts — and four or more in another suit, or a single-suited hand of at least six cards in the bid suit, in a hand worth 5-10 HCP.

See also

References
  1. "Muiderberg". Bridge Guys. Retrieved 7 November 2015.
  2. Manley, Brent; Horton, Mark; Greenberg-Yarbro, Tracey; Rigal, Barry, eds. (2011). The Official Encyclopedia of Bridge (7th ed.). Horn Lake, MS: American Contract Bridge League. p. 282. ISBN 978-0-939460-99-1.

Bibliography
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