H. G. Muller wrote on Fri, Jan 21, 2011 01:37 PM UTC:
I don't think you give a correct summary of those Xiangi rules. At least, not for the rules I know ('Asia rules'). For one, the condition is for causing any repeated position, not just consecutive. (So just like in FIDE Chess.) The difference with FIDE rules is that a 3rd repeat is not automatically draw, but can also be judged as win or loss. A side that is somehow forcing the repetition will be ruled to lose, where forcing by checking is considered a worse offense than forcing by merely attacking a superior or unprotected non-royal piece ('chasing'). So that if both are continuously forcing each other, the checking side loses. To be counted as a perpetual check or chase, every move of the repeat loop must be a forcing move threatening the same piece; if there is only one 'quiet' move (even a mate-in-1 threat) in the loop, or a move that only threatens another piece, (even if that is a check amongst chases), it is not considered perpetual check or chase.
The exact rules for which moves are to beconsidered forcing, and which not, are so complex that it requires a sizable AI to implement them. (See http://www.clubxiangqi.com/rules/asiarule.htm )
China mainland rules seem to be even more complex (even mate threats counting as forcing), and I have never been able to find an English description of them.