November 2020 - 41

Newer Players

Parrish the Thought
BY ADAM PARRISH

adam@adamparrishbridge.com

adamparrishbridge.com

Single-dummy vs. double-dummy mistakes
When you hear the term "double
dummy," it simply means playing as if
you can see all four hands and making
the best play as the cards lie. You'll never lose to a singleton king or take the
wrong finesse playing double dummy.
This is what those Deep Finesse
numbers on hand records mean: It's
what happens if a computer plays the
deal knowing where all the cards are. It
doesn't mean it's what you should do,
just what you could do if you could see
all the cards.
Single dummy, conversely, means
you have only the information you
would have at the table - your hand,
the dummy, the auction and the play.
Playing for real at the bridge table is
playing single dummy.
Broadly speaking, we can lump all
our mistakes into two categories:
double-dummy mistakes and singledummy mistakes. A double-dummy
mistake means you would have played
differently if you could see all the
cards: you took a losing finesse, you
didn't play for the bad trump split,
etc. A single-dummy mistake means
you played against the odds; given the
information you had, there was an alternative that rated to work out better
in the long run.
It's possible, even common, to make
a single-dummy mistake that works
out on a given deal. Here's a simple
example:

♠KJ654
♠A32
We all know "eight ever, nine never,"
so absent any conflicting information,
taking the finesse is the percentage
play: Cash the ♠A, then lead to the ♠J.
Say this is the layout:
♠KJ654
♠ 10 9 8

♠Q7
♠A32

If you could see all the cards, of
course you wouldn't take the finesse.
But without this omniscience, the right
play is still to finesse.
It's important for us to differentiate
between our single-dummy mistakes
(not taking the finesse) and doubledummy mistakes (taking the finesse).
A mistake that only Deep Finesse
would get right isn't something to
worry about. It's when we make the
wrong play, given the information we
have, that we want to focus on - even
when it works out, as in the case above.
It seems obvious to concentrate on
our low boards - where we score under,
say, 20% - to look for our mistakes.
There's usually one there, but not
always. Maybe the opponents just did
something brilliant. Or made a mistake

that worked out for them (like not taking the finesse above).
But it can also be valuable to look at
our high scores. Why did we do better than everyone? It could be that we
did something brilliant. Good for us. It
could be that our opponents did something wrong. We can learn from their
mistakes as well.
But there are times when a good
score might indicate a mistake. On the
example above, if you play the ♠A and
then ♠K - a single-dummy mistake -
you will score well, because everyone
else will presumably make the percentage play of taking the finesse. You
might get a stone-cold top for taking
a trick more than everyone else. The
worst thing you can do is pat yourself
on the back for being brilliant here: You
made a mistake! Even bad plays work
out sometimes. Don't let a learning
opportunity slip by just because your
mistake worked in your favor this time.
When a board looks pretty normal,
but you do better than everyone else,
especially the Flight A players, it's
likely you made a single-dummy mistake that worked out double dummy.
This is as valuable for you to learn from
as the more common deals where your
mistake cost you.
◾

November 2020 Bridge Bulletin

41
http://www.adamparrishbridge.com
November 2020

Table of Contents for the Digital Edition of November 2020
