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Subject: Re: "Threat" function in Fritz 7, Nullmove & example

Author: Mike S.

Date: 10:55:46 04/10/02

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On April 10, 2002 at 09:44:17, Jeroen van Dorp wrote:

>From the help file:
>
><quote>
>Menu: Help – Threat (or Shift-T)
>
>Displays the immediate threat, (i.e., what the opponent could do if no
>defensive move is made). (...)

The threat display is a key usability feature IMO. I'm not aware at the moment,
if any other chess program except Fritz (and others using the Fritz GUI) has
that. The ChessBase database program has it too.

It can be done in *every* chess program of course, by going into the setup
function, switching the color who has the move, and starting the analysis. But
this looses the game history, and is uncomfortable... AFAIK no program has an
easy GUI switch to change the color to move (and allows to keep the game
history).

It is very useful during (manual) analysis, i.e. in cases when mysterios moves
are played, which may often turn out that this was necessary to *defend* a deep
threat. Also, the sense (and strength) of many moves can often be understood
better calculating the threat with that function. CB programs have another
feature (which is also not very common AFAIK), connected to that: They can
insert *nullmoves* into the notation (not to be confused with nullmove
algorithms in the search). This inserts an variation starting with an "empty"
move for the side which has the move, and allows to enter the threat like a
normal variation. Without that nullmove, you could only display the threat as a
text comment, but not as an variation easily *replayable* at the board.

These are example features aimed at practical usefullness, which distinct very
good chess programs (GUIs) from "just good" ones IMO. By that, engines get also
more usability value.

An example from an old rapid chess game Fritz 3 - Mephisto Lyon 16 Bit:

[D]4r1k1/2p2pp1/2pp3p/p6q/1r3B2/QP1P2Pb/P3PP1P/2R1R1K1 w - - 0 24

Black's last move was 23...Bh3. Programs will play moves here, which lose
material: 24.g4 Qxg4+, or 24.Qb2 Rxf4 (25.gxf4?? # in 2).

Why? The threat function will display the answer quickly (ok, strong chess
players may quickly find it themselves too... what's the first move of Black's
threat? Test yourself :o).

Regards,
M.Scheidl



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