From 51a23d7b74601f8630d16041c38d15cef767fe0e Mon Sep 17 00:00:00 2001
From: Petr Baudis <pasky@ucw.cz>
Date: Tue, 9 Mar 2010 12:49:53 +0100
Subject: [PATCH] tex: Pattern Features updates

---
 tex/gostyle.tex | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/tex/gostyle.tex b/tex/gostyle.tex
index 2174f0b..8f0afaf 100644
--- a/tex/gostyle.tex
+++ b/tex/gostyle.tex
@@ -426,30 +426,36 @@ each dimension of player's \emph{pattern vector} is scaled to range $[0,1]$ and
 therefore even players with different number of games in the database have comparable \emph{pattern vectors}.
 
 \subsection{Pattern Features}
-TODO sladit aby to navazovalo na predchozi odstavec
-
-Of course a big question is how to compose the pattern descriptions.
+We need to define how to compose the patterns we use to describe moves.
 There are some tradeoffs in play - overly general descriptions carry too few
 information to discern various player attributes; too specific descriptions
-gather too few specimen over the games and the differences in vectors are
+gather too few specimen over the games sample and the vector differences are
 not statistically significant.
 
 We have chosen an intuitive and simple approach inspired by pattern features
 used when computing ELO ratings for candidate patterns in Computer Go play.
 \cite{ELO} Each pattern is a~combination of several {\em pattern features}
-matched at the position of the played move. We use these features:
+(name-value pairs) matched at the position of the played move.
+We use these features:
 
 \begin{itemize}
-\item board edge distance
 \item capture move flag
 \item atari move flag
 \item atari escape flag
-\item spatial pattern --- a configuration of stones around the played move,
-with differentiated color to play; configurations with diameter between
-2 and 9 are matched\footnote{The diameter determines maximal distance from
-center in the {\em gridcular} metric: $d(x,y) = |\delta x| + |\delta y| + \max(|\delta x|, |\delta y|)$}
+\item contiguity-to-last flag --- whether the move has been played in one of 8 neighbors of the last move
+\item contiguity-to-second-last flag
+\item board edge distance --- only up to distance 4
+\item spatial pattern --- configuration of stones around the played move
 \end{itemize}
 
+The spatial patterns are normalized (using a dictionary) to be always
+black-to-play and maintain translational and rotational symmetry.
+Configurations with diameter between 2 and 9 in the gridcular metric%
+\footnote{The {\em gridcular} metric
+$d(x,y) = |\delta x| + |\delta y| + \max(|\delta x|, |\delta y|)$ defines
+a circle-like structure on the Go board square grid. \cite{SpatPat} }
+are matched.
+
 \subsection{Implementation}
 
 We have implemented the data extraction by making use of the pattern
-- 
2.11.4.GIT