Understanding Card Marks
Central to working with Deep Finesse is understanding the
and
card marks. Try running one of the demo deals and
you will see that at each player's turn, all legally playable
cards are labeled with a
or
.
A card labeled with a
is termed a
"winning card" because playing it results in a winning
position. Similarly, playing a "losing card" results in
a losing position. A winning position for North-South means that
declarer can always make the contract with correct play against
any defense. A winning position for East-West means that proper
defense can always set the contract against any line of declarer
play.
As long as the side with the winning position continues to
make sound plays, they are assured of reaching their objective -
namely making or setting the contract. Only by playing cards
labeled with a can one reach or maintain a winning
position. Choosing a losing play when winning plays were
otherwise available is a blunder, and the winning position will
shift to the other team. Of course, the team that is stuck in a
losing position will have nothing but losing plays to choose from
unless their opponents blunder at some point.
In addition to the and
marks, a
is attached to the card that has won the
current trick. Don't confuse a "winning play" with
"winning a trick." Sometimes deliberately losing a
trick (ducking) is the only way to make or set a hand. A card
play that wins the current trick might be a losing play for the
contract as a whole. Similarly, a card play that deliberately
loses the trick might be the only winning play available.
When you change the line of play by clicking on a new card, Deep Finesse will automatically re-compute and re-label the winning and losing plays from that point onward. If South leads a winning card to a certain trick, for example, then West will have nothing but losing plays available to him. If you change South's lead by clicking on a losing card in his hand, winning plays will suddenly appear in West's hand.
Deep Finesse normally displays card marks on all legal plays.
You can turn off the card marks by clicking the toggles in the
lower left of the screen. The author, for example, prefers to
turn off the marks to reduce screen clutter. In this
mode, if a card is not labeled with a
then by inference it
must be a losing play (or illegal).
Sometimes you may see cards labeled with a .
That means Deep Finesse is still evaluating that card play. It
will be converted to a
or
when analysis is complete. For more, see Understanding
Hand Analysis.