After a 1st-round Double

From Simplex

The Principles of 1st-round Doubling

Simplex Principles of 1st-round Doubling

PRINCIPLE 11: If a bidder cannot make the first-round bid his hand merits (because the opposition have already taken the auction too high), the bidder simply doubles, with an implied message to partner: "RHO has just taken my opening bid away, and I believe it is safe for you to bid at this or one level higher." PRINCIPLE 13: Ignore first-round doubles by the opponents. Carry on and make the bid you would have made if the opponents had passed. PRINCIPLE 17: Be very wary about doubling when both opener and responder have taken your bid away. You are usually too weak. (For example, you have a hand worth opening 1♣ but the bidding has already gone (1♦):Pass:(1♠).) Exceptionally you can double at the one and two levels when you have 11+ HCP and you are distributional (e.g. a 5-5 shape or a 6+ card suit). PRINCIPLE 30: Do not double their strong (i.e. 16+ HCP), natural bids.

Box O1A (Version 1.0)	Opening, Overcalling and Doubling
Bid	Meaning	Forcing?	Where to next?
Pass	Hand does not satisfy any of the criteria below.	NF	-
One of a Suit	Five or more cards, 8-16 HCP (and 'Bad Seventeens'), Rule of 18 compliance, no suit quality necessary, and no longer suit.	NF	Box R1A
1NT	11-16 HCP (and 'Bad Seventeens') and no suit longer than four cards. It does not require a stopper in any enemy suit(s). A distribution of 4-4-4-1 is fine.	NF	Box R1B
Two of a Suit	Six or more cards, 3-16 HCP, no suit quality necessary, and no longer suit.	NF	Box R1C
Three of a Suit	Four or more cards, 17-22 HCP (excluding 'Bad Seventeens'), and no longer suit. Bad Seventeens are flat 17 HCP hand containing five or more losers, which should be opened at the one-level.	NF	Box R1D
2NT	23+ HCP, any shape.	GF	Box R1E
Double	8+ HCP. "I had an opening bid, but the opponent's bid to my right just took it away." (To be used against all except their strong bids.)	NF	Box R1F

The Principles for Responding to a 1st-round Double

Simplex Principles of Responses to a 1st-round Double

PRINCIPLE 0: Almost always open, overcall and respond with your clearly longest suit. (That is, except when responding to an opening/overcall of Three of a Suit, when it is often better to bid one's cheapest 4+ card suit.) PRINCIPLE 22: Always bid the cheaper of two equal-length suits.

Bids available to Responder when responding to a 1st-round Double

Box R1A (Version 1.0)	Responding to One of a Suit (1♣, 1♦, 1♥, 1♠)
Bid	Meaning	Forcing?	Where to next?
Pass	0-7 HCP and less than 3-card support for partner's suit	NF
Double	Unable even to bid 1NT. RHO's overcall has taken his bid away.	NF	Box O2A
One of a New Suit	5+ cards, 8-16 points, compliant with Rule of 18.	NF	Box O2B
1NT	8-16 HCP and no other available bid — i.e. the 'dustbin' bid. The hand will contain fewer than four cards in opener's suit. The hand may contain four cards in another suit, or a 5-card suit not now biddable at the 1-level.	NF	Box O2B
Two of a New Suit	6+ cards and 3-16 points	NF	Box O2B
Raise to Two of the Suit	3-card support and 0-9 HCP	NF	Box O2C
2NT	4+ card support and 10+ HCP	F	Box O2B
Three of a New Suit	4+ cards and 17+ HCP	GF	Box O2B
Raise to Three of the Suit	4-card support and 0-9 HCP	NF	Box O2D
Raise to Four of the Suit	5-card support and 0-9 HCP	NF	Box O2E
Raise to Five of Opener's Minor	6+card support and 0-9 HCP	NF	Box O2F

The Principles for Opener's/Overcaller's 2nd Round Bid

Simplex Principles of 1st Round Responses to One of a Suit

PRINCIPLE 6: If Opener/Overcaller rebids his suit on the second round, this shows a suit longer than the five cards originally promised. A simple rebid — e.g. 1♥ then 2♥ — shows a 6-card suit. A jump rebid — e.g. 1♣ then 3♣ — shows a 7-card suit. (NB This principle is not enforced if responder showed a strong hand in the first round — i.e. 2NT, 3x, or 4NT.) PRINCIPLE 7: No extra values are needed to bid any 4+ card suit at the two-level on the second round. There is no concept of a 'barrier' or a 'reverse'. PRINCIPLE 9: Simplex is a fundamentally natural bidding system. The only gadgets used are 2♣ Redshift, 4NT Blackwood, and the Simplex 2NT. PRINCIPLE 12: After a suit-raise by partner — e.g. 1♦:2♦ or 1♥:3♥ or 1♠:4♠ or 1♣:5♣ — do not bid on. That is, unless the opponents are trying to steal your contract and you have extra suit length beyond the five cards your initial bid promised. PRINCIPLE 20: After opening/overcalling One of a Suit or 1NT or doubling on the first round, you can bid another 4+ card suit at the 2-level on the second round, even if responder passed. PRINCIPLE 21: If you had a hand worth opening at the 1-level and you have another 5+ card suit, you should bid it at the 3-level on the second round, even if responder passed. PRINCIPLE 26: After the second round, your doubles are for penalties — do not double purely because RHO has just taken your bid away. PRINCIPLE 28: 2NT in reply to a suit bid is always the Simplex convention. 2NT in reply to 1NT is always quantitative, showing 12-14 HCP balanced.

Box O2B (Version 1.0)	Opener's Rebid after opening One of a Suit (1♣, 1♦, 1♥, 1♠)
Responder's Bid	Opener's Rebids	Meaning	Forcing?	Where to next?
One of a New Suit	Pass	Minimum opening hand (i.e. 8-12 HCP), little support for responder, no other 4+ card suit.	NF
	One or Two of a New Suit	4+ card suit.	NF
	1NT	11-16 HCP and fairly balanced with a 5-card suit.	NF
	Rebid of Opener's original suit at the 2-level	6-card suit.	NF
	Raise Responder's suit to the 2-level	3-card support and less than 10 HCP.	NF
	2NT	The Simplex 2NT: 10+ HCP and 4+ card support for Responder's suit.	NF
	Rebid of Opener's original suit at the 3-level	7+ card suit.	NF
	Raise Responder's suit to the 3-level	4-card support and less than 10 HCP.	NF
	Raise Responder's suit to the 4-level	5-card support and less than 10 HCP.	NF
	Raise Responder's minor to the 5-level	6-card support and less than 10 HCP.	NF
1NT	Pass	8-10 HCP and a 5-3-3-2 shape.	NF
	Rebid of Opener's original suit at the 2-level	6-card suit.	NF
	Two of a New Suit	4+ card suit.	NF
	2NT	12-14 HCP, balanced or semi-balanced.	NF
	Rebid of Opener's original suit at the 3-level	7+ card suit.	NF
	3NT	15+ HCP, balanced.	NF
Two of a New Suit	Pass	Minimum opening hand (i.e. 8-12 HCP), little support for responder, no other 4+ card suit.	NF
	Two of a New Suit	4+ card suit.	NF
	Rebid of Opener's original suit at the 2-level	6-card suit.	NF
	2NT	The Simplex 2NT: 10+ HCP and 4+ card support for Responder's suit.	NF
	Raise Responder's suit to the 3-level	3-card support and less than 10 HCP.	NF
	New Suit at the 3-level	5+ card suit.	NF
	Rebid of Opener's original suit at the 3-level	7+ card suit.	NF
	Raise Responder's suit to the 4-level	4-card support and less than 10 HCP.	NF
	Raise Responder's minor to the 5-level	5-card support and less than 10 HCP.	NF
2NT	Rebid of Opener's suit at the 3-level	Up to 13 HCP.	NF
	Cue-bid of cheapest 1st-round control	14+ HCP.	F
Three of a New Suit	Rebid of Opener's original suit at the 3-level	Minimum opening hand (i.e. 8-12 HCP), less than 4-card support for responder, no other 4+ card suit biddable at the 3-level.	NF
	Three of a New Suit	4+ card suit.	NF
	3NT	Balanced, preferably with the other two suits stopped.	NF
	Rebid of Opener's original suit at the 4-level	6+ card suit.	NF
	Raise Responder's suit to the 4-level	3+ card support and 8-12 HCP.	NF
	4NT	Blackwood: 13+ HCP.	NF

2nd Round Bids available to Opener/Overcaller