[computer-go] GTP and handicap

[Mark Boon]

Today I was looking at a final problem I had with Goliath when  
playing through GTP, which was handicap. Whenever I tested it with  
GoGui it seemed to play strangely in the opening when I set some  
handicap. It turned out that GoGui wasn't using any of the handicap  
commands (since kgsGTP uses setFreeHandicap I had blindly assumed  
GoGui did the same) but it played several black moves at the start  
instead.

Since Goliath was never made to allow the same color to move more  
than once in a row, the handicap stones were alternately black and  
white, which explains the strange openings. I had to add a bit of  
code to cope with that, which wasn't much of a problem once I figured  
what was going on.

But it left me wondering what is the use of all the different  
handicap commands. GTP is designed to accept moves of the same color  
in a row so whoever implements it must be able to cope with it too.  
The 'place_free_handicap' command can be done through sending  
subsequent 'genmove black' commands. It would clean up the protocol  
and you no longer need the rather long explanation about handicap  
placement either.

Mark