[ Joseki engine ]

This is a joseki pattern scanner. At the beginning, you should
have SGF files with various joseki as variations. Right now there's
one sgf file for each type of corner sequences:

	joseki_33.sgf    sansan variations
	joseki_34.sgf    komoku variations
	joseki_44.sgf    hoshi variations
	joseki_54.sgf    takamoku variations

They started as "a few simple variations to get Pachi to do the right
thing when playing without dcnn" (patterns are terrible at joseki), but
by now quite a few variations from Kogo joseki dictionary have made it
in. There are some non-joseki variations as well (good answers to bad
moves), some of which come from Leela-Zero ELF for things that are not
in Kogo. It's by no means complete or exhaustive, the idea here was:
start with basic variations, let Pachi play with human players, see what
kind of joseki mistakes it does, fix these. Rinse and repeat ...

Previous Pachi versions contained a recipe for automatically extracting
joseki sequences from Kogo, however starting from scratch gives more
flexibility and control:

For example at 3k level there's no point in Pachi playing large avalanche
or taisha joseki, it will screw up at first unknown deviation. So right
now it chooses simple variations to avoid them. Also it's a lot easier
to enforce consistent conventions for tenuki and we can also support
joseki deviations so it can have good answers to bad moves.

joseki module is disabled when playing with dcnn:
dcnn can handle joseki mostly, and josekifix module takes care of fixing
cases it handles poorly.

To generate the joseki database from sgf variations type:

	cd joseki ; make data

this will (re)create joseki19.gtp. If Pachi finds it it will use it to
match joseki patterns and guide tree search when playing without dcnn,
and optionally in playouts as well if MOGGY_JOSEKI is defined (disabled
by default, slow).


[ Conventions ]

The SGF files can contain any sequence of moves / setup stones etc,
however there are guidelines to follow to get the joseki engine to do
the right thing. Moves can be any color and don't have to be in a
particular quadrant. First line of comments is reserved for tags which
give move special meaning, if there are none first line should be empty
(actual comments may follow).

Cheatsheet:
-----------------------------------------------------------------------------------------------------------------
                            |                           |  pattern |  matches prev ?    |          |  
type of move                |         sgf               |  radius  |      move          |   prio   |  gogui
-----------------------------------------------------------------------------------------------------------------
normal move                 |    regular move           |    4     |        y           |   high   |  red/orange
match 3x3 pattern only      |    tag: <3x3>             |    1     |        y           |   high   |  circle
mistake                     |    tag: <don't>           |    4     |        y           |    -     |  cross
tenuki followup (urgent)    |    2 moves in a row       |    4     |        y           |   high   |  red/orange
tenuki followup (later)     |    pass <later> + move    |    4     |        y           |   low    |  yellow
                            |    or move <later>        |          |                    |          |
match with extra stones     |    setup stones + move    |    4     |        n           |   low    |  yellow


Spatial patterns:
The joseki engine matches based on spatial patterns. For a move to match
the situation around both the move to play and the previous move in the
joseki sequence must match. The spatial pattern is a circle of radius 4
currently, so if there's any extra (or missing) stone on the board within
4 stones of the previous move or move to play there won't be a match.
Usually this is fine for corner sequences, but if the sequence extends
to the side existing stones on that side can interfere. 

Match 3x3 pattern only:
To get around that either add extra variations with setup stones for the
existing stones you want to match (...) or tag that move <3x3>. Only the
3x3 pattern around that move will be checked and more distant stones will
be ignored. Prev move in the sequence must still match fully, so it won't
just match any random situation. 

Ignored moves:
Moves tagged <don't> <bad> or <avoid> are ignored: they won't match as
joseki moves (pachi won't play them), however if opponent does pachi will
know how to answer. Useful to include good answers to bad moves, trick
plays, deviations etc.

Setup stones:      (disrupt the sequence)
Setup stones are treated as out-of-sequence stones, there's no pattern 
matching around them but of course they affect pattern matching of following
moves. Setup stones disrupt the sequence: following move will be treated like
the first move in a sequence, ie matched without previous move. This can be
good or bad depending on the situation: it will get lower priority than a
normal answer-to-previous move, and without previous move less context is
checked so it might match more situations than intended.
To get a strong match after setup stones add previous move as ignored move:

    [ setup stones -> ignored move -> move ]
                       (prev move)

Tenuki variations:
  - urgent: [ change color, play 2 moves in a row ]      (2 black moves for example)
            -> high priority move
  - later:  [ pass <later>, next move ]  or just
            [ next move <later> ]
do not play elsewhere, say another corner or move will be matched !
Pass moves must be tagged <later> or <tenuki> (same thing).


[ Testing / Visualizing ]

Start pachi in gogui, then

  Tools -> Analyze commands -> Joseki Moves

Shows matching joseki moves for current board (red: strong matches,
yellow: weak matches, cross: ignored move with followup sequence),
circle: 3x3 pattern match only.

  Tools -> Analyze commands -> Joseki Range

Shows joseki spatial pattern range around clicked coordinate (4 stones radius).