[mike777]

Can anyone describe how a spiral scan works?


For this thread I was just wondering how to combine that with Kickback(rkc) responses?

[Fluffy]

When I googled it I understood that it worked like this: you rank all the keycards in an order, for example ♣K♦K♥K♠K♣Q♦Q♥Q♠Q♣J

Then the asker bids first step, and the responder bids the step of the first card HE IS MISSING, hence if he doesn´t hold ♣K in my example he bids first step, if he has ♣K♦K but no ♥K he bids third.

Asker can gain space by bidding second step instead of first to avoid a card he is holding himself and gain a step.

This is mainly used for strong club systems were no trump has been stablished I think. Won´t combine very well with kickback.



In our strong club system we use some form of keycard asking stablishing trumps at low level, and then we use something that we call spiral, because it derives a bit with the original idea, but actually has nothing to do with it, it has negative responses also and has more steps for asker. I think something similar can be applied to kickback for grand exploration, if you want it I´ll show.

[mike777]

Fluffy, on 2011-November-23, 16:35, said:

When I googled it I understood that it worked like this: you rank all the keycards in an order, for example ♣K♦K♥K♠K♣Q♦Q♥Q♠Q♣J

Then the asker bids first step, and the responder bids the step of the first card HE IS MISSING, hence if he doesn´t hold ♣K in my example he bids first step, if he has ♣K♦K but no ♥K he bids third.

Asker can gain space by bidding second step instead of first to avoid a card he is holding himself and gain a step.

This is mainly used for strong club systems were no trump has been stablished I think. Won´t combine very well with kickback.



In our strong club system we use some form of keycard asking stablishing trumps at low level, and then we use something that we call spiral, because it derives a bit with the original idea, but actually has nothing to do with it, it has negative responses also and has more steps for asker. I think something similar can be applied to kickback for grand exploration, if you want it I´ll show.

thanks

[hrothgar]

mike777, on 2011-November-23, 16:22, said:

Can anyone describe how a spiral scan works?

For this thread I was just wondering how to combine that with Kickback(rkc) responses?

I don't think its practical to combine spiral scan with kickback (not enough bidding space)
It's also unclear whether spiral scan is efficient outside the context of a relay system.

With this said and done, here's a simple version (My MOSCITO notes have a much more detailed treatment)

Spiral scan is a mechanism by which one player describes which controls are held in which suit.
Typically, the relay responder has already described how many slam points or, alternatively how many controls he has.
Furthermore, some kind of scanning order needs to be establish. (The scanning order denotes in order in which the relay responder will show controls)
Playing relay methods, where responder's complete shape is known the scanning order is typically arranged

longest suit
second longest suit
third longest suit
shortest suit

Ties are broken in order H > S > D > C


As a practical example, let's assume the following (preliminary) auction

1♣ - 3♦
3♥ - 3N

1♣ was strong
3♦ show 3=1=5=4 shape
3H asked for slam points
3N shows 7 slam points

At this point in time, 4♣ kicks off spiral scan with order D-C-S-H

A 4♦ response would show either 0 Diamond Honors or AKQ in Diamonds
A 4♥ response would show 1-2 Diamond honors and either 0 Club Honors or AKQ in Clubs
A 4S response would show 1-2 Diamond honors, 1-2 club honors, and 0 Spade honors.
A 4N response would show honors in Diamonds, Clubs, and Spades and deny the Ace or King of Hearts
A 5C response would show a second Diamond honor, but deny a second Club honor

Relay captain can make repeat asks to place additional controls. For example, assume that relay responder bid 4H

If the relay captain bids 4S he is asking responder to continue the scan, starting with Spades, then Hearts, then back to Diamonds

[gnasher]

What's wrong with combining it with Kickback? It's more efficient than standard trump queen and king-asks. You just have to be clear about which bids are signoffs rather than asking.

For example, with hearts agreed it might go
4♠-4NT (Kickback / 1/4)
5♣-5♠ (Spiral / ♥Q + ♠K, no ♦K)
6♣-6♠ (Spiral, skipping ♣K / ♠Q + ♦Q, no ♣Q)

[PrecisionL]

10 years ago I played spiral scan in a Precision System.

Now, we play denial cue bids in a more complex 1 Club strong system. The spiral scan (there is a book on it) took a lot of time even though we simplified it. I really prefer denial cue bidding.

Rosenkranz may have been first with it:

http://www.bridgeguy...SpiralScan.html

http://193.156.107.6...lish/spiral.htm

[blackshoe]

A book on the spiral scan? What book?

The method is described in several of Rosenkranz's books on Romex. I first ran across it in Bridge: The Bidder's Game (1985), and later in Bid to Win, Play for Pleasure (1990).

It does work well with Kickback, but you do, as Andy mentioned, need to be clear about which bids are sign-offs.

[Free]

hrothgar, on 2011-November-23, 16:46, said:

Ties are broken in order H > S > D > C

As usual I found a typo it should be H > S > C > D

[hrothgar]

Free, on 2011-November-24, 00:18, said:

As usual I found a typo it should be H > S > C > D

Sadly, free is correct on both counts

[shevek]

Free, on 2011-November-24, 00:18, said:

As usual I found a typo it should be H > S > C > D

Our little group plays S > H > D > C.
Above may offer a small theoretical advantage but compliance costs would be major after all these years.
Anyway, in responding to 1C, we show S > H > D > C, like most. There is merit in consistency.

[Mbodell]

shevek, on 2011-November-24, 18:37, said:

Our little group plays S > H > D > C.
Above may offer a small theoretical advantage but compliance costs would be major after all these years.
Anyway, in responding to 1C, we show S > H > D > C, like most. There is merit in consistency.

What is the theoretical advantage? I also show length first, then break ties S > H > D > C for our denial cue bidding. It seems logical to me.

[Zelandakh]

I also break ties from the highest suit down, and the same for relay breaks to decide which stops can be queried when space is limited. That said, I cannot say what I play is spiral scan since aces and kings are treated equally as per denial cues and relay breaks are (mostly) to play. I have to admit I thought spiral scan was more common with a fixed trump suit as after Kickback than in straight relaying. It is certainly much simpler that way as it is very clear which bids are asking and which are sign-offs.

[Free]

It's difficult to explain, but the small edge you get from playing H>S>C>D is primairily when your longest suits are equal and you're in a borderline case. The order is based on the order of game scores for suit contracts, which is 4♥, 4♠, 5♣, 5♦. When the 2 longest suits are equal in length, trump quality may be most important. During a scan, the relay responder usually doesn't know which suit is trumps (exceptions are possible). In this case you don't want to give one trump suit more advantages than another. When playing high to low, ♠ gets an advantage over ♥, and ♦ gets an advantage over ♣, without a clear reason.

Example: RR showed a 1=2=5=5 and relayer starts the scan with 4♥. Say skipping a step shows 1-2 top honours.
When playing SHDC (high to low), RR will have the following responses:
4♠ = 0/3 ♦ honours
...4NT = continue scan
...5m = signoff
4NT = 1/2 ♦ honours, 0/3 ♣ honours
...5♣ = continue scan
...5♦ = signoff
...6♣ = signoff
When playing HSCD:
4♠ = 0/3 ♣ honours
...4NT = continue scan
...5m = signoff
4NT = 1/2 ♣ honours, 0/3 ♦ honours
...5♣ = continue scan
...5♦ = signoff
...6♣ = signoff

In both cases, it's not possible to stop at 5♣ when the first step is skipped, however, the chance is smaller that you'll want to signoff in 5♣ when RR shows 1 or 2 ♣ honours than when responder shows 0 or 3 ♣ honours (which usually means 0). When RR shows 0 top honours in a minor suit, we can always sign off in that minor at 5-level playing HSCD. This is not always possible playing SHDC. (note: I'm sure there are better examples, but this one shows the principle quite nicely)

As I said, it's a small advantage, and doesn't come up that often. But if you're used to it, you don't make any mistakes against this, so why not apply it? If it does come up, you'll do better on that deal.

[PrecisionL]

blackshoe, on 2011-November-23, 20:13, said:

A book on the spiral scan? What book?

Found the book I had in mind, SWEEP Q-BIDS by Ted Brashler, 1985.

NOTE: It is somewhat different from Spiral Scan as the controls (or lack of) are shown in order (up-the-line) after suit agreement and not by importance or suit length as in Spiral Scan.

[Siegmund]

I wondered if that might be the book you had in mind.

A really excellent book which completely changed the way my reg p and I approached our slam auctions. We did make a few minor changes to Brashler's presentation, but the method deserves much more publicity than it gets.

[benlessard]

SS is IMO very underated. In a relay system it lead to very interesting bidding problems.

?????
???
????
?

Qx
Kxx
Axxx
AKQ

1C--1H(S)
1Nt--2C(D)
2D--2S (low short and S>D) GF values
2Nt---3C (5341)


playing strong clubs south showed 15-20 without 3S and north show 5341 with GF values.

Here declarer could think about bidding 3nt because of major C wastage but hes got 18 pts and D fit (he could have 15) so he continue. Having already denied 3S the order for trumps are. DHS so he bid 3D. Responder may not be slammish at all but he can lie with keycard if he thinks that game is the absolute limit.

3D-- 3S (30)

3Nt (QD ask or to play if possible that its 0)---4C No DQ (confirming at least slightly slammish)

The next cards after Q of trumps is Ks,Kh,Qs,Qh,Jd,Js,JH

4D (Ks ?)---4S (yes but no KH).

The next cards after K of H are Qs,Qh,Jd,Js,JH,

Here we know that
AK???
A??
K???
?

without Q of D

With nothing else 6D need 3/2 break while 6nt need 3-3 S break (poor)
With QH 6Nt is best 6S is 2nd 6D will go down with 4-1 break
with QH+JS 7nt while 6D can go down.
only JS 6S is very slightly better than 6Nt becasue you may still make if D are 4-1 and S are 5-1
the 3 Jacks 7Nt has very good play.

He we see that 6D,6S,6NT,7Nt are possible as best contract. Here we had space enough to be ok but oftne space is limited and choosing wich cards to ask is nightmarish.