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Rule of 7 and 17 Ever hear of these rules? What are they

#41 User is offline   Zelandakh 

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Posted 2020-December-13, 20:36

View PostDavidKok, on 2020-December-13, 07:20, said:

I have not run into the fact the LTC 'pretends to be something else', but I guess that is simply a blessing. Pretentiousness aside, why is it substandard? Which alternatives have it beat, as a quick-and-dirty guideline similar to the MWC?

Here is (I think) my first BBF post on the subject back in 2012. I have posted similar in more detail since if you run a search.

The reason the MLTC works (the original LTC is genuinely just bad) is because of the 3-2-1 counting for aces, kings and queens. Studies suggest that pretty much every point count method that uses this in some form outperforms simple MWC for suit contract evaluation. Some examples are AKQ control points (3-2-1) and Zar points (6-4-2). Thus the way to make MWC competitive is to add half a point for aces and subtract half a point for queens, giving 4.5-3-1.5. This puts MWC and MLTC on the same footing for most honour holdings so the differences come from shortages.

As I point out in the linked post, if you do the scaling MLTC effectively uses values of 9-4.5-1.5 for voids-singletons-doubletons. Studies suggest that more accurate figures are closer to Goren's 5-3-1 and Zar's 2(2a+b-d)/3 (where a is the longest suit; b the second longest; and d the shortest) also turns out to be generally accurate, if not exactly matching the required simplicity. Finally, MLTC values K, Q and Qx as zero. It is surely correct to devalue these holdings from their normal values but MWC offers the possibility of coming in somewhere between full value and zero.

The main point here is that most players undervalue shortages. MLTC compensates by overvaluing them, which is a useful learning tool for many players. Once you get it though, it is (imho) easier and much more accurate just to go back to MWC and make the appropriate adjustments - upgrade aces, downgrade quacks (particularly unsupported quacks), downgrade honours in short suits and give full value to shortages. In the end though, it is the 3-2-1 / 4.5-3-1.5 / 6-4-2 values that work as the basis for all of these suit-based evaluations, so as long as you use a method starting from there, the rest is just fine-tuning and judgement.
(-: Zel :-)

Happy New Year everyone!

#42 User is offline   thepossum 

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Posted 2020-December-14, 12:39

I don't know about you but I'm happy to consider any system or method proposed by a world expert on Bridge rather than a group of unknowns on a discussion forum 🙂

First discovered LTC a few years ago via debate on here, read Klinger and I think my bidding improved almost overnight, especially on decisions over part score, game, slam exploration. Also use similar loser count to decide on borderline opening bids

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