Astro Roth-Stone
This conventional defense method was devised by Mr. Alvin Roth and Mr. Tobias Stone, two very successful bridge players, partners, and authors. This version of the Astro convention, employed after a No Trump opening by the opponents, shows a two-suited holding of two known suits. This advantage of knowing which two suits are meant from the very first bid is enormously informative to the advancer.
The concept of this version is that a two-suited holding is defined as either a minimum of 5-5 distribution or a 6-4 distribution, whereby the 6-card suit is a Minor suit. A minimum of 10 high card points is mandatory. However, this restriction was less rigid when both suits were both Major suits. The parameters for both Major suits were defined as a holding with a minimum of 5-4 distribution, a minimum of 10 high card points, and most values concentrated in the Major suits, not in side suits.
The overcalls by the intervenor are shown below. The significance of the overcalls were not changed based on the state of vulnerability. These bids were made in the immediate seat following the opening of No Trump by an opponent. Any application of these bids following two passes is strictly per partnership agreement.
The following examples illustrate the effectiveness of this conventional defense method against an opening of No Trump by the opponents.
| Opponent |
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Overcaller |
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Meaning |
| 1 NT |
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Double |
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Promises a one-suited holding with a minimum of a 6-card suit. In the case that the partner of the No Trump bidder passes, then the advancer will relay with 2 . The intervenor will either pass or correct. |
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The advancer, with sufficient values has the option of either bidding 2 or passing the double of the No Trump for penalty. A second option of the advancer is to bid a new suit besides Clubs, the relay suit, to show a long, independent suit of at least 7 cards either in Diamonds, Hearts, or Spades.
| Opponent |
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Overcaller |
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Meaning |
| 1 NT |
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3  |
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Preempt in Spades. Generally a 6-card plus suit. |
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These two examples show the difference between a one-suited holding and a preemptive bid. The conventional defense method, as devised by Mr. Alvin Roth and Mr. Tobias Stone, categorically states that a double and/or a suit overcall be made with a minimum of 10 plus points. The preemptive bid can be made with fewer points.
If you wish to include this feature, or any other feature, of the game of bridge in your partnership agreement, then please make certain that the concept is understood by both partners. Be aware whether or not the feature is alertable or not and whether an announcement should or must be made. Check with the governing body and/or the bridge district and/or the bridge unit prior to the game to establish the guidelines applied. Please include the particular feature on your convention card in order that your opponents are also aware of this feature during the bidding process, since this information must be made known to them according to the Laws of Duplicate Contract Bridge. We do not always include the procedure regarding Alerts and/or Announcements, since these regulations are changed and revised during time by the governing body. It is our intention only to present the information as concisely and as accurately as possible.