[TomReynold]

This is a RFC (Request for Comment) on a system for combating interference over a big Club 16+HCP. Comments and suggestions for improvements are solicited. I understand that the formatting lost while posting her makes following the logic difficult. If you would like a copy in word or pdf format please email tomreynolds_ilan@yahoo.com or send me a message here.

Mavarako System Competition over a Forcing Club

Theory of Operation
In the mini Spingold 2015 most pairs played either nothing or Mathe. (Double for Majors, 1NT for the minors.) Via a simple overcall, the goal of the opponents is to disrupt the club system sequence and, if a fit is found preempt to the appropriate level. Further, if responder becomes declarer, the opening leader can lead through the club opener’s hand, hopefully finessing the club opener on the opening lead.

The Mavarako system seeks to negate those goals.

Most modern Club systems play transfer responses, at least in the majors. A few show controls. However, once the opponents intervene I submit transfer responses are indicated as opposed to controls. The danger of preemption is simply too great.
Most systems employ a card showing double by responder (1C-1H-X) of an intermediate strength (5-9HCP) to show opener that responder has some values. After interference over 1C, Mavarako also uses a card showing double but only with a balanced hand. This modification tells the club opener that in addition to some values, opener can expect some support in responder’s hand.
In addition, the last thing Mavarako wants the opponents to do is lead the overcalled suit THROUGH the club opener. Therefore, Mavarako plays four suit transfers by responder. The level of transfer indicates the length of the suit responder is transferring. 1C-1D (overcall)-1H shows responder has 4+ Spades, 1C-1D (overcall)-2H shows responder has 5+ spades. Opener need not accept the transfer if he is unbalanced.

Although designed for Mavarako, the system for handling competition over a forcing club is also applicable for most systems employing a forcing club such as Precision, Neapolitan or Blue Team. However the HCP ranges may need to be adjusted.

Mavarako System
The Mavarako System employs a forcing club that is 16+HCP for any hand that can rebid 1H, 1S or 1NT, 17+HCP for hands that rebid clubs and 18+HCP for a hand that will rebid 2D. Responses are:
1D 0-6(7) or 11+HCP
1H 7-11 showing 4 Spades
1S 7-11 showing 4 Hearts
1NT 8-10 Natural
2C, 2D 7-10 Natural, no 4 card major
2H-2S 8-11 Smolen type (5-4) major two suiters
2NT 12+HCP Natural
3C and above transfers showing a 0-1 loser suit and at least 1 Ace
Bids marked “no change” are following this structure.

Precision Systems
Precision Systems using a 16+ HCP Club should adopt the Mavarako ranges.
Precision Systems showing 17+HCP unbalanced or 18+HCP balanced should drop the response HCP range 1HCP

Neapolitan System
Neapolitan and Blue Team systems showing 17+HCP balanced should drop the response HCP range 1 HCP

General Rules
One level Interference
1. 1NT is natural
2. All suits are transfers except 2C/1D
3. 2S is an artificial game force
4. 2NT and above no change
5. Excluded Transfer is a club transfer or Stayman
6. Double is card showing

Two level Interference
1. 2S is an artificial Game force except for the flip-flop over 2D
2. Excluded Transfer is Stayman
a. If the excluded transfer is 3NT or 3C, it is puppet Stayman
3. 2NT is a Club transfer
4. X is a negative double

Three Level Interference
1. After 3D transfers stop
2. 4 Clubs is a major two suiter

Single suit (Natural) on the one level
One level bids of 1S or less typically do not, by themselves, disturb the Club auctions. The major suit transfers and responses remain. This is by design. Mavarako’s goal is that a cheap overcall by opponents should not disturb Mavarako’s carefully coded responses. In contrast, the overcall should help. If the overcall is a single suit transfer, responder should bid as if opponent’s real suit was bid. Responder’s bids marked (No Change) means opener should respond as if the interference didn’t happen.
The danger is that overcaller’s partner may have a fit and attempt to jam the auction. Thus there are additional transfers on the two level to allow the partnership to find their fit and play from the strong side. Over intervention and a raise Mavarako’s coded sequences are disturbed. However, the tradeoff is the information gained.

General rules
With 0-6 HCP responder passes.
4 Suit transfers.
Double is takeout and should not be passed
If opener refuses a transfer and bids diamonds (potentially artificial) he is showing a big hand

Over 1C-1D-?
X takeout. Invites opener to bid 1NT with a balanced hand.
1H transfer with 4+ Spades, semi-positive minimum (No Change)
1S transfer with 4+ Hearts, semi-positive minimum (No Change)
1NT-no change
2C Natural 5 card suit
2D transfer to Hearts , 5 Card suit
2H transfer to Spades, 5 card suit.
2S artificial game force
2NT 12+ (No Change)
3C and above are transfers (No Change)

Over 1C-1H-? (Or 1C-1D showing hearts.)
X transfer to 1S. Essentially the same as bidding 1H (Transfer) (No Change)
1S denies 4 Spades. Potentially a club transfer.
1NT Natural (No Change)
2C Transfer to Diamonds (1C-1H-2C ♦-P-2H (Shows Spades)
2D (excluded transfer = Stayman),
2H Transfer to Spades, 5 card suit
2S artificial game force
2NT and above no change

Over 1C-1S
X Negative Double (shows 4 Hearts)
1NT Natural
2C Diamond Transfer [1C-1S-2C(Diamond transfer)-P-2D-P-2S (shows 4 Hearts +5 Diamonds)]
2D Heart Transfer
2H Club Transfer [1C-1S-2H (Club transfer)-2NT/3C- 3S (Shows 4 Hearts +5 diamonds)
2S is an artificial game force
2NT and above no change

Single suit (Natural) on the two level
With 0-6 responder passes.
X is takeout but may be passed
3C is Puppet Stayman over 1C-2C and 1C-2D, Excluded Transfer (3D) is Stayman over 2H
2 Spades is an artificial game force except for flip-flop over 2D
2 Suit bids over 1C-2H and 1C-2S
If opener refuses a transfer and bids diamonds (potentially artificial) he is showing a strong hand

Over 1C-2C
Pass is 0-6 or a penalty X. Responder assumes that opener will reopen with 16+ and short Clubs. Over a reopening double responder bids 2D with weakness. This allows opener to bid 2H or 2S.
X is takeout at least semi positive.
2D is a transfer to Hearts
2H is a transfer to Spades
2S artificial game force
2NT Puppet Stayman (excluded transfer)
3C Diamond Transfer
3D is a Heart Transfer (Longer Hearts)
3H is a Spade Transfer (Longer Spades)
3S shows club shortness
3NT to play

1C-2D
x- semi-positive
2H is a Spade Transfer (5 Spades)
2S Is a Heart Transfer (5 Hearts)
2NT is Club Transfer. (If over the transfer responder bids anything but 3D he has a diamond stopper)
3C is Puppet Stayman
3D is a Heart Transfer (Longer Hearts)
3H is a Spade Transfer (Longer Spades)
3S shows Diamond shortness
3NT to play

1C-2H
X semi-positive
2S artificial game force
2NT is Club Transfer
3C is a Diamond Transfer
3D excluded transfer is Stayman.
3H is a Spade Transfer
3S asks for a Heart Stopper

1C-2S
X-is a takeout double that can be passed
Over X 3H shows 5 hearts by opener
Over X 2NT does not deny 4 Hearts (responder Bids 3S over 2NT to show 4 Hearts)
2NT transfer to clubs.
Any other bid by responder other than 3D shows a stopper)
1C-2S-2NT (transfer to C)-P-3C accepts transfer-P-4D shows a diamond heart 2 suiter.

3C Transfer to Diamonds
3D Transfer to Hearts
3H Stayman or minor 2 suiter
3S asks for a Spade stopper
3N to play
4C 2 suiter Clubs and Hearts
4D 2 Suiter Diamonds and Hearts

Single suit on the 3 level

With 0-7 responder passes
A pass says either responder has a penalty double or a weak hand.
A double is semi-positive or better.
A new suit is semi-positive or better

1C-3C
X-Takeout double that can be passed
A bid of 3D by opener is game forcing, potentially artificial, and does not deny a 4 card major. Responder bids the major he does not have. A bid of a major by opener shows 5
3D Transfer to Hearts
3H Transfer to Spades
3S Transfer to 4D (or 3NT)
3NT natural
4C major 2 Suiter
4D Transfer to Hearts
4H Transfer to Hearts

1C-3D
X Takeout Double that can be passed
3H Transfer To Spades
3S Transfer To Hearts
3N Natural
4C Natural Clubs
4D Transfer to Hearts
4H Transfer to Spades

1C-3H
X Takeout double that can be passed
3S natural
3NT natural
4C natural
4D natural
4H Transfer to Spades

1C-3S
X takeout double that can be passed
3NT to play
4C Natural
4D Natural
4H Natural

Two-Suit Competition
A new suit is semi-positive or better. Over competition, it is important for the responder, with a semi-positive response, to get his suit in early. Partner may well have a 15-16NT. Therefore, responder bids a natural suit whenever possible to show 7+ HCP. Except for the natural NT response new suits are forcing.

In the 2015 Chicago Nationals Mini-Spingold, either Mathe or Suction was played by the opponents

Versus Suction

Suction either is a transfer to the next suit or it shows the succeeding two suits:
1C-X shows Diamonds OR Hearts and Spades
1C-1D shows Hearts or Spades and Clubs
1C-1H shows Spades or Clubs and Diamonds
1C-1S shows Clubs or Diamonds and Hearts
1C-1N shows Clubs and Hearts
1C-2C shows Diamonds and Spades

There are variations on this theme. However this scheme is easy to remember because the Suction bidder never has the suit he initially bids.

Not understood, Suction is confusing. Once understood, however, Suction has the weakness that overcaller’s partner (advancer) does not know partner’s suit any more than opener or responder.

This gives responder the opportunity to pass with a penalty double of overcaller’s transfer suit.
[1C-X (showing diamonds)-P!-1D-P-P (showing diamonds)-X (penalty double Diamonds).

It also means that, after passing, if responder transfers into the overcaller’s suit he shows a penalty double of the transfer suit [1C-X-P!-1D-P-1H (I have Hearts and Spades)-2C (transfer to Diamonds. I had a penalty double of Diamonds)]

One Level
1C-X Showing Diamonds or Hearts and Spades
XX semi positive showing clubs
1D takeout double of Diamonds (essentially the equivalent of 1C-1D(natural)-X (take out double)
all other bids are the same as if overcaller overcalled 1D natural

1C-1D Showing Hearts or Spades and Clubs
X semi positive showing Diamonds
1H Shows 4+ Spades
1S Shows 4+ Hearts (Overcaller may not have Hearts)
all other bids are the same as if overcaller overcalled 1H

1C-1H Showing Spades or Clubs and Diamonds
X Shows 4+ Spades
1S Shows 4+ Hearts
all other bids are the same as if overcalled 1S

Two Level
Bidding over Suction becomes more difficult on the two level. The point to remember is that, in Suction, the first bid is always the suit the Suction bidder does not have.

1C-1S showing Clubs or Hearts and Diamonds.
Pass Does not necessarily deny a good hand. Responder may want to punish overcaller. However opener should treat a pass as negative until shown otherwise. Pass, then double by responder is penalty.
X balanced card showing double
1NT Natural w/Clubs
2C Transfer to diamonds
2D Transfer to Hearts
2H transfer to Spades, 5 card suit
2S artificial game force

1NT showing rounder suites Suits (Clubs and Hearts)
X balanced card showing double
2C transfer to Diamonds
2D Stayman (Puppet) Opener bids 2H with 4 Spades, 2 Spades with 5 Spades, 2NT natural
2H Transfer to Spades
2S artificial game force
2NT natural

2C showing pointed Suits (Diamonds and Spades)
X balanced card showing double
2D transfer to Hearts
2H Stayman (Puppet). Opener bids 3 H with 5, 2S with 4, 2NT natural
2S Artificial game force
2NT natural
3C natural

Versus Mathe

Over 1C-x showing the majors
1 Pass is negative
2 XX is a semi-positive Club response
3 1D is a semi-positive Diamond response
4 All other bids are unchanged

Over 1NT showing minors
1 Pass is negative
2 X shows a desire to punish
3 2C is a Heart Transfer
4 2D is a Spade Transfer
5 2H/2S are unchanged (4-5 in the majors)
6 3C is puppet Stayman

Versus Brozel:

X and xx show semi positive response in the other suits
Transfers at lowest possible level
Openers bid of a major shows 5. Responder may re-ask with 4.
Higher cue bid shows positive response

1. X Clubs and hearts
a. XX semi-positive negative double diamonds and spades
b. 1D natural semi-positive
c. 1H Spades Transfer (4+ Spades)
d. 1S Diamonds Transfer
e. 1NT natural and semi-positive
f. 2C positive response 11+ (puppet Stayman)
g. 2H Spades Transfer 5+

2. 1D diamonds and hearts
a. X semi-positive clubs and spades
b. 1H Spade Transfer (4+)
c. 1S Club Transfer
d. 1NT natural and semi-positive
e. 2C, 3C natural semi-positive
f. 2D positive response 11+ (puppet Stayman) (2H shows 4 Spades)
g. 2H Spades Transfer (5+)

3. 1H hearts and spades
a. X minors semi-positive
b. 1S Diamond Transfer
c. 1NT semi-positive natural
d. 2C natural semi-positive
e. 2D, 3C natural and semi-positive
f. 2H positive response 11+

4. 1S Spades and a minor
a. X takeout hearts at least semi-positive
b. 1NT natural and semi-positive
c. 2C natural and semi-positive
d. 2D Heart Transfer (5+)
e. 2H Diamond Transfer
f. 2s positive 11+

Versus Cappelletti

1. X One suited hand (equivalent to 2 Clubs over NT)
a. XX semi positive Clubs
b. 1D semi-positive Diamonds
c. 1H, 1S, 1NT, 2H, 2S unchanged
d. 2C, 2D positive Diamonds

2. 1 Diamond (Majors)
a. X minors semi-positive
b. 1S Diamond Transfer
c. 1NT natural and semi-positive
d. 2C Semi-positive Clubs
e. 2D Positive Clubs 11+
f. 3C natural and semi-positive
g. 2H positive Diamonds 11+

3. 1H Hearts and a minor
a. X card showing double
b. 1S Diamond Transfer semi-positive
c. 1NT natural and semi-positive
d. 2C semi-positive Clubs
e. 2D Positive 11+ Clubs
f. 2H Spade Transfer
g. 2S Positive 11+ Diamonds
h. 3C natural semi-positive

4. 1S Spades and a minor
a. X card showing double
b. 1NT natural and semi-positive
c. 2C Semi-positive Clubs
d. 2D Heart Transfer
e. 2H Diamond Transfer
f. 2s positive

Club Opener rebids after interference

General rule is that the first available pass by a Club opener denies 17+HCP.
In a live auction:
• A double by club opener confirms 16+HCP and is for takeout
• A voluntary Club bid by the club opener confirms Clubs and 17+ in clubs
• A Major suit bid by club opener is 16+ unbalanced
• 2D is 18+ If responder has passed he responds as if the auction went 1C-1D-2D

In a non-live auction:
• 1NT , a raise of a semi-positive response show the 16-17HCP range
• Major suit shows 16+, Clubs 17+, Diamonds 18+
• A simple response to a cue-bid may be 16-17HCP or better

As one can easily see, interference at a low level essentially helps the club opener partnership if the club opener is unbalanced.
 

[straube]

Your 1C-1D is weak or strong? How about....1C (1D) P=weak and dbl=strong? You can show these and one more thing after 1C dbl.

I like 1C (2L) 2N to be GF with a stopper. 1C (2L) 2S then shows the "missing" suit. 1C (1L) 1N also GF with a stopper because nf with a stopper seems pretty rare.

[TomReynold]

Over 1C-1D (natural) I chose to keep the Mavarako structure which is transfer 1H and 1S bids. Pass is weak. Double is takeout inviting opener to bid 1NT.

Our experience is that when responder makes a semi-positive response, a possible slam is in the cards if the club opener is large. Mavarako opens 1C with hands other systems may open with 2NT.