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Key to the Use of PERTO Reports
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The "Tabbed" Report
-------------------

*Note: if your editor has a "tab-spacing" option, the chart below appears
best at a spacing of "5"
------------------------

a - 1...e5 {107}, c6 {34}, e6 {25}, d6 {19}, Nf6 {7}, g6 {7}, d5 {3}, Nc6 {1}
b - 1...Nf6 {299}, d5 {173}, d6 {15}, e6 {11}, f5 {6}, g6 {6}, Nc6 {1}
c - 2...Nf6 {97}, d6 {33}, b6 {10}, e5 {4}, g6 {4}, Qa5 {1}, Nc6 {1}, a6 {1}
d - 2...cxd4 {11}
e - 3...Nf6 {3}
f - 4...Nf6 {127}, Nc6 {27}, e5 {7}, g6 {2}
g - 4...exd5 {19}
h - 5...cxd4 {3}, Qd8 {2}, Nc6 {1}
i - 6...Qd8 {1}

1.		2.		3.		4.		5.		6.		7.		8.		9.		10.
-------- 	-------- 	-------- 	-------- 	-------- 	-------- 	-------- 	-------- 	-------- 	--------
d4	c5	e4	{512/1}
	(b)		(d)

e4	c5	c3	d5	exd5	Qxd5	d4	e6	Na3	Nf6	Nb5	Na6	Be3	cxd4	Qxd4	Qxd4	Bxd4	b6	Be2	Bb7	{998/2}
	(a)		(c)		(e)		(f)		(h)		(i)

e4	c5	c3	e6	d4	d5	exd5	Qxd5	{27/6}
	(a)		(c)				(g)

e4	c5	d4	d5	exd5	Qxd5	c3	e6	{11/1}
	(a)		(d)				(f)
--------------------------------------------------------------
Above is the analysis file produced by a line taken from the game (below)
where White, 2576-rated Andrei Kharlov, played a Sicilian Alapin. Since the
line scores very well for White, one might wish to consider it in one's
repertoire as a response to 1...c5. (One advantage of the Alapin arises
from an early reduction of alternatives permitted to the opponent.)

To discover what alternatives must still be met, PERTO.exe was used to
perform an analysis of the position of the game after 10.Be2 Bb7. In the
process, PERTO analyzed approximately 350 B22/09 games; 350 general B22
(Alapin) games; and 1100 games from a general collection--covering all
openings. The analysis was from White's perspective--therefore no
alternative moves are shown for White.

In the 1800 total games there were only four possible move sequences which
achieved the position (or followed it to some point). Once White played
7.Be3, there were no further Black "stoppers" through the remainder of the
line. There were, however, a total of three games which reached the 7.Be3
position--all White wins.

Now, return to the chart above....to the most common line, beginning,

	1.e4 c5 2.c3 d5 3.exd5

At the top of the chart are the "stoppers" -- the alternatives Black has at
his disposal to steer clear of the key position. We can ignore alternative
(a) - 1...e5 if we assume that we have at least entered Sicilian territory.

The next alternative Black has is (c) - 2...Nf6 with 97 games found in the
analyzed collections. This is a real possibility and should be reserved for
a second PERTO study. After that though we have (e) - 3...Nf6 with only
three games (quite rare).

Next, are stoppers (f), (h), and (i). Only (f) is significant enough to
deserve our attention. If Black does not play 4...Nf6 (and our hoped-for
4...e6 is much the more common move), then we have a very real possibility
of achieving our pre-selected position or one very similar to it.

In summary then, this is the simple game start that PERTO has helped us
put together,

	1.e4 c5 2.c3 d5 (Nf6/d6) 3.exd5 Qxd5 4.d4 e6 (Nf6) 5.Na3

In truth, the confidence level for amateur games is less well-founded but
it would be rare for a GM, playing the Black pieces, to stray too far from
the above line or its alternatives.

------

Incidentally, the numbers, e.g., {998/2} following the lines are, 1). the
number of partial move sequences that held for at least a part of the line,
and, 2). the number of games which reached the terminal position of the
line.  Don't put too much stock in the first number as--depending upon the
collating sequence of the sorted move strings--one will get credit for (eg)
all 1.e4 games (not of the opening being considered) that happened to fall
above it. This will always happen to at least one line when a general
collection is used as one of the searched game files.

For a quick look at the Line Report, see the text following the game below.

[Event "?"]
[Site "Leeuwarden NED"]
[Date "1994.??.??"]
[Round "01"]
[White "Kharlov Andrei"]
[Black "Zilberman Yaacov"]
[WhiteElo "2576"]
[BlackElo "2477"]
[Result "1-0"]
[ECO "B22/09"]
[Opening "Sicilian: Alapin's Variation"]
1.e4 c5 2.c3 d5 3.exd5 Qxd5 4.d4 e6 5.Na3 Nf6 6.Nb5 Na6 7.Be3 cxd4
8.Qxd4 Qxd4 9.Bxd4 b6 10.Be2 Bb7 11.Bf3 Bxf3 12.Nxf3 Nd7 13.O-O-O f6
14.Rhe1 e5 15.Be3 Be7 16.Rd5 Nf8 17.Nh4 Ne6 18.Nf5 g6 19.Nxe7 Kxe7 20.f4 e4
21.Bf2 f5 22.Bh4+ Kf8 23.g3 Kg7 24.Rd7+ Kh6 25.b4 Rhc8 26.Kb2 Nac7
27.Bg5+ Kh5 28.Rxh7+ Kg4 29.Re3 1-0


The Line Report
---------------
  {512/1} 1.d4 c5 e4 1/2
  {998/2} 1.e4 c5 c3 d5 exd5 Qxd5 d4 e6 Na3 Nf6 Nb5 Na6 Be3 cxd4 Qxd4 Qxd4 Bxd4 b6 Be2 Bb7 1/2
   {27/6} 1.e4 c5 c3 e6 d4 d5 exd5 Qxd5 1/2
   {11/1} 1.e4 c5 d4 d5 exd5 Qxd5 c3 e6 1/2

The same lines that appeared in the Tabbed Report (above) are produced in
the Line Report. These will allow you to play back the actual moves from
the lines selected (use chess reader ChessU4) or to trace through the lines
with Tree-Searcher ChessU3. In the case of the Alapin, there are few lines
produced, but some complex 1.d4 openings, such as the D44 Semi-Slav, produce
pages of lines--all reaching the same position.

If you have a postal or correspondence game going in an opening that has
many transpositions, ChessU3 is particularly handy. Don't assume, just
because your opponent played a move outside a listed line, that you have
been taken "out of position." Run the Line Report through ChessU3. ChessU3
uses all moves as stepping-stones and will often find a move in the report
that puts the game back on track. Thus, it will find lines--using the
report of lines--that do not exist in the report itself.

If using ChessU3, mark the longest line--the one that defines the
sought-for position--with a "1-0" terminator. This will made it easy to
trace towards the desired, final position.


	-Paul Onstad 70641.3236@compuserve.com

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