" - "sohl is one of the best conventions ever invented, I'd say. Reasons? It solves a real and very frequent problem, how to differentiate strength when opps pre-empt. Also it gives up relatively nothing: 2NT as natural bid? Why on earth... better just pass and try to set them or gamble 3NT.
I count there are three different sohls available, each with it's own advantages and thus places to use. These are the old fashion Lebensohl, Rubensohl and the modern transfer-Lebensohl or "Rumpelsohl" as I heard it called. I'm trying to give a good write up for them all and places where to use them. I note here that I'm using here a nonstandard way regarding stoppers. I have direct 3NT showing a stopper, direct cuebid denying one, and via sohl they are opposite. This is because it seems practical often to just blast that 3NT, especially if your 3NT is based on some source of tricks and LHO might raise if you bid it slow. Do whatever you wish regarding stoppers, just so that you remember which way shows what.
For introductory purposes I'm now assuming 1NT opening that is interfered with natural 2 level overcall.
So we have 1NT (2C/D/H/S) ? sequences to handle with three different sohls.
Lebensohl:
Basic idea is that 2NT is a puppet to 3C to play in any suit lower than the opponent's suit, bid stayman showing a stopper by cuebidding or show depending on agreements, inv/gf in higher than opp's suit. Let's see the simplest auction where opponent bids 2S:
1NT (2S)
->
2NT = Lebensohl
3C/D/H = Natural and GF
3S = GF with 4H and no spade stop
3NT = GF without 4H and a spade stop
4x = Here you have some options, for example you might play system on. I play SA Texas so 4C/D would be transfers for me. You might also want to use some Leaping Michael's scheme here. Just agree on something.
1NT (2S) 2NT (P) 3C (P)
->
P = Weak/Competitive with clubs
3D/H = Weak/Competitive
3S = GF, 4H, spade stopper
3NT = GF, no spade stop or 4H
Again for 4lvl, you got another way to bid them, try to get some use of them. I suggest them being slammish when bid slowly, preferably some spade length so opps won't be wildly pre-empting after 2NT.
For lower opponent overcalls you get some extra bids to define.
1NT (2D)
->
2H/S = Weak/Competitive natural
2NT = Leb
3C = Nat, GF
3D = GF, stayman
3H/S = Nat, GF
3NT = GF with stopper
Going via 2NT, you get extra 3H/S bids. You can have many different meanings for these things. I guess the standard is that direct denies stopper and going via leb shows one. That's certainly playable. I'd prefer to have some invites available so I'd use direct bids for invites and go slow with GFs.
1NT (2C) (Note that very few play this as natural, so you hardly ever need this sequence)
Here we lose the second way to cuebid, but we can get along with one cue as it's so low:
1NT (2C) 3C (P)
->
3D = No club stopper, may have one or both majors still
3H = 4H, may have 4S, club stopper
3S = 4S, club stopper
3NT = No 4 card majors, club stopper
Rubensohl:
Basic idea is that every bid starting from 2NT up to one below opp's suit is a transfer to the next suit, either weak or GF. Starting with opp's suit, bids are transfers showing inv+ values.
1NT - (2H)
->
2S = Weak/Competitive natural
2NT = Clubs, weak or GF
3C = Diamonds, weak or GF
3D = GF, 4S, may or may not have a stopper (you have room to find out)
3H = Spades, inv+
3S = Transfer to 3NT, no 4S and no stopper but GF
3NT = To play
Transfer-Lebensohl:
The point is to take good from both of the above and get invite bids. Starting from 2NT everything is a transfer, similar to Rubensohl but 2NT in addition works as a multi-way bid including all the weak/competitive hands as well.
1NT (2H)
->
2S = Weak/Competitive natural
2NT = Transfer to C, either weak with C or D, or GF with clubs
3C = Inv+ with D
3D = GF, 4S
3H = Inv+ with S
3S = GF, transfer to 3NT, no 4S and no stopper
3NT = To play
1NT (2S) (This would be normal)
->
2NT = Transfer to C, weak with C/D/H or GF with clubs
3C = Inv+ D
3D = Inv+ H
3H = GF, 4H
3S = GF, no stopper nor 4H
3NT = To play
My preferred:
1NT (2S)
->
2NT = Transfer to C, weak with C/D or GF with clubs
3C = Inv+ D
3D = Inv+ H
3H = Weak/Competitive with hearts
3S = GF, 4H
3NT = To play
Point is to get the heart hand bid directly cause we might want to bid 4H sometimes and it's not possible if LHO bids 3S. We lose the stopper ask with GF and 4H and the really rare hand where you have no 5 card suit, no spade stopper, no 4H and a GF. I think I'll just try my luck in 3NT anyways.
Lebensohl is the basic and really easy version if you ask me. It gives you lot's of sequences but you miss on the chance of bidding invite hands. Opposite some narrowly defined NT opening it's not much of a problem, but considering a sequence like (2H) X (P) it has uses to be able to differentiate 3 ranges. Also Lebensohl has the problem that you are not telling your suit right away. This could especially be a problem for those hands you bid "slow" over the opp's suit. Leb does nicely give you another set of 4 lvl bids if you can put them to good use.
Rubensohl corrects the problem of showing the shape right away and gives you inv+ bids for suits over the opp's. Opponents get many chances to double for lead though and they can even psyche it with some support for partner's suit. You get better ways for bidding slam hands as you have whole lot of room after transfer acceptance. Just have to agree on some continuations. You also sometimes end up losing room after T/O double sequences: (2S) X (P) 3D, but you happened to hold monster with diamonds as the doubler. If you played leb, you could have bid 3D over 2NT. But if you work on continuations, it's definitely an improvement over Leb.
"Rumpelsohl" is the Swiss army knife of sohls. You get weak and GF bid for every suit and invitational bid for all but clubs. You're not showing your weak suit directly so partner can't compete fit like after Rubensohl, though on the other hand he knows you don't have a light invite so it might be better not compete anyhow. Similarly as on Rubensohl, you must work on continuations to take the most out of playing this version of sohl, but if you put in the work, I'd say it's definitely the best.
Sequences where to apply:
I already gave the two most common examples, after 1NT is overcalled and after opponent opens a weak two and partner makes a T/O double. Other sequences might be: (1M) P (2M) X (P), this is quite similar to opening weak two, though if they play constructive raises, scrambling might be better. Also over weak jump overcall after our minor opening: 1C (2M), is a good sequence to take advantage of sohl type approach. You must of course make some adjustments depending on the situation what each bid shows. If partner's 1C opening shows 4 cards, my 2NT doesn't show 5-6 cards like it would over 1NT opening. Then again for stopping in diamonds after club opening, I prefer to have that 6 card suit as partner hasn't promised any support. Keeping these in mind, you can apply sohl very frequently in many auctions.
Oh and one thing I haven't mentioned: Agree what it means if partner doesn't accept the transfer, ie. bid 3C over 2NT. It tends to depend on the context, after 1NT opening it should promise very good club support while after T/O double it should show some monster hand that was too strong to overcall in a suit.
