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Subject: Re: Amateur chess program released

Author: Dann Corbit

Date: 19:04:07 02/15/00

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On February 15, 2000 at 20:50:37, Andrei Fortuna wrote:
[snip]
>It enters xboard mode automatically, no -xboard needed. To run it with winboard
>run winboard and enter [Frey's path]\freyr.exe as the first chess program. To
>use it from the command line to analyze an epd file use it with the following
>parameters :
>
>	-analyse <epd filename>
>	-outfile <filename to write results to>
>	-maxtime <max time for a position to be analysed in 1/100 seconds (float)>
>	-maxply <max ply to analyse a position>
>	-tag <engine configuration description when analysing EPDs>
>
>like in
>
>freyr.exe -analyse wac.epd -outfile wac.txt -maxtime 26000 -maxply 5 -tag "5
>plies fab"
>
>I apologize for the poor documentation, it was released without very much
>efforts put into user friendlyness. I'll release in about a week a new &
>improved version, which will include among others a readme.install & an option
>to build the opening book from a pgn.

Now that I see how to use it, I like your program a lot.  I do see a lot of
error messages about null pv's (for example):
Analysing position : 4r3/1Q1qk2p/p4pp1/3Pb3/P7/6PP/5P2/4R1K1 w - - bm d6+; id
"WAC292";
Best move converted d6+
Test move : [d6+]
+---+---+---+---+---+---+---+---+
|   |   |   |   | r |   |   |   |
+---+---+---+---+---+---+---+---+
|   | Q |   | q | k |   |   | p |
+---+---+---+---+---+---+---+---+
| p |   |   |   |   | p | p |   |
+---+---+---+---+---+---+---+---+
|   |   |   | P | b |   |   |   |
+---+---+---+---+---+---+---+---+
| P |   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+---+
|   |   |   |   |   |   | P | P |
+---+---+---+---+---+---+---+---+
|   |   |   |   |   | P |   |   |
+---+---+---+---+---+---+---+---+
|   |   |   |   | R |   | K |   |
+---+---+---+---+---+---+---+---+

    2.  -184    0       178     Qxa6(p) Qxh3(p) Rf1
    3.  -175    0       1511    Qxd7(Q) Kxd7(Q) Rb1 Rb8 Rf1
    4.  -180    0       5029    Rb1 Rb8 Qxd7(Q) Kxd7(Q) Rxb8(R) Bxb8(R)
    5.  -91     0       18645   d6 Ke6 Qb3 Kf5 Qc4 h5 Qxa6(p)
    6.  203     0       37023   d6 Ke6 Qb3 Kxd6(p) Rd1 Kc7 Rxd7(Q) Kxd7(R) Qb7
Kd6 Qxh7(p)
    7.  203     1       87094   d6 Ke6 Qb3 Kxd6(p) Rd1 Kc7 Rxd7(Q) Kxd7(R) Qd5
Ke7 Qb7 Kd6 Qxh7(p)
Null length PV !
Time to analyse position : 5.01 seconds

And also, I have a feature request to correct your ce for checkmates (at least
the ce that you report).  From the PGN Standard by Steven J. Edwards:

"16.2.5.6: Opcode "ce": centipawn evaluation

The opcode "ce" indicates the evaluation of the indicated position in centipawn
units.  It takes a single operand, an optionally signed integer that gives an
evaluation of the position from the viewpoint of the active player; i.e., the
player with the move.  Positive values indicate a position favorable to the
moving player while negative values indicate a position favorable to the
passive player; i.e., the player without the move.  A centipawn evaluation
value close to zero indicates a neutral positional evaluation.

Values are restricted to integers that are equal to or greater than -32767 and
are less than or equal to 32766.

A value greater than 32000 indicates the availability of a forced mate to the
active player.  The number of plies until mate is given by subtracting the
evaluation from the value 32767.  Thus, a winning mate in N fullmoves is a mate
in ((2 * N) - 1) halfmoves (or ply) and has a corresponding centipawn
evaluation of (32767 - ((2 * N) - 1)).  For example, a mate on the move (mate
in one) has a centipawn evaluation of 32766 while a mate in five has a
centipawn evaluation of 32758.

A value less than -32000 indicates the availability of a forced mate to the
passive player.  The number of plies until mate is given by subtracting the
evaluation from the value -32767 and then negating the result.  Thus, a losing
mate in N fullmoves is a mate in (2 * N) halfmoves (or ply) and has a
corresponding centipawn evaluation of (-32767 + (2 * N)).  For example, a mate
after the move (losing mate in one) has a centipawn evaluation of -32765 while
a losing mate in five has a centipawn evaluation of -32757.

A value of -32767 indicates an illegal position.  A stalemate position has a
centipawn evaluation of zero as does a position drawn due to insufficient
mating material.  Any other position known to be a certain forced draw also has
a centipawn evaluation of zero."

You seem to be using a long string of 9's (not without precedent -- e.g. Rebel
and some others do the same thing):
Analysing position : 2r1kb1r/pp3ppp/2n1b3/1q1N2B1/1P2Q3/8/P4PPP/3RK1NR w Kk - bm
Nc7+; id "WAC267";
Best move converted Nc7+
Test move : [Nc7+]
+---+---+---+---+---+---+---+---+
|   |   | r |   | k | b |   | r |
+---+---+---+---+---+---+---+---+
| p | p |   |   |   | p | p | p |
+---+---+---+---+---+---+---+---+
|   |   | n |   | b |   |   |   |
+---+---+---+---+---+---+---+---+
|   | q |   | N |   |   | B |   |
+---+---+---+---+---+---+---+---+
|   | P |   |   | Q |   |   |   |
+---+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+---+
| P |   |   |   |   | P | P | P |
+---+---+---+---+---+---+---+---+
|   |   |   | R | K |   | N | R |
+---+---+---+---+---+---+---+---+

    2.  -27     0       214     a3 Ra8 Nf3
    3.  368     0       3173    Nc7 Rxc7(N) Qxc6(N) Bd7 Qxc7(R) Bxb4(p)
    4.  1268    0       5455    Nc7 Rxc7(N) Qxc6(N) Bd7 Qe4 Qe5 Qxe5(Q) Be6
Qxc7(R) Bxb4(p)
    5.  1268    0       16509   Nc7 Rxc7(N) Qxc6(N) Bd7 Qe4 Qe5 Qxe5(Q) Be6
Qxc7(R) Bxb4(p)
    6.  99999999        0       30139   Nc7 Rxc7(N) Qxc6(N) Bd7 Qe4 Qe5 Qxe5(Q)
Be6 Rd8
Time to analyse position : 1.36 seconds

All in all, I like your engine very much.  Hmm... a second feature request
(which you are free to ignore just like the first one):
Create EPD analysis in standard EPD format.  It is so much more useful that way.




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