After a One of a Suit Opening/Overcall

From Simplex

The Principles for Responder's 1st Round Bid

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

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 5: 1NT, whether bid as an opening, overcall or response, does not claim a stopper in any suit bid by the opponents. PRINCIPLE 9: Simplex is a fundamentally natural bidding system. The only gadgets used are 2♣ Redshift, 4NT Blackwood, and the Simplex 2NT. PRINCIPLE 10: Responding hands with trump support but less than 10 HCP bid immediately to their total trump level. (For example, after a 1♥ opening by partner, a hand containing 6 HCP and four cards in the heart suit would immediately raise to 3♥. Partner is known to have at least five hearts. Add those five to the four that responder has makes nine. Take six from nine means a raise to the 3-level.) Equally if opener has less than 10 HCP but support for responder's suit, he will bid to the total trump level on the second round. 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 16: In response to an opening of One or Two of a Suit, responder shows a hand worth a good raise to at least Three of the Suit — i.e. 10+ HCP and 9+ trumps between them — by bidding the Simplex 2NT. If Responder bids a suit on the 1st round, a rebid by opener of 2NT shows that opener has 10+ HCP and that the pair have at least nine cards in responder's suit. And if Opener changes suit on the second round, Responder can bid the Simplex 2NT in reply, showing 10-16 HCP and 4+ card support for Opener's second suit — e.g. 1♥:1♠, 2♣:2NT. PRINCIPLE 18: An opening bid, overcall or response of Three of a new Suit guarantees four or more cards in the suit and 17-22 HCP. PRINCIPLE 19: Responder's first-round responses to an opening of one or two of a suit should be: Show support for partner's major. If you are weak (0-9 HCP), show support for partner's minor. Make the bid you would have made, had you been opener. If you are strong (10+ HCP), show support for partner's minor. Show support for partner's minor. Double the opposition's bid if it has taken away your opening bid. Bid 1NT with 8-16 HCP and no biddable suit. PRINCIPLE 22: Always bid the cheaper of two equal-length suits. PRINCIPLE 23: Except for strong (17+ HCP) hands and responses to doubles, four-card suits are never explicitly bid in the first round. PRINCIPLE 30: Do not double their strong (i.e. 16+ HCP), natural bids.

1st Round Bids available to Responder

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