Single Comment

'Move borrowing' is already implemented as an overloading of the 'induction' modifier x: in its original use the x could be used in the non-final leg of a multi-leg move description, to indicate it should end on a friendly piece, and that the remaining legs then should be performed by the piece landed on, rather than the piece for which the move was calculated. Because it did not seem useful to induce null-moves in other pieces, the case where there were no remaining legs (i.e. when the x is used on the final leg) was later defined to do the reverse: it made the original piece move as the piece on which the x-leg ended.

Of course the 'move borrowing' could have been considered move induction by the piece that is borrowed from on the piece that is borrowing, but variants that have this feature typically limit such induction to one specific target type (the move borrower), while genuine induction would typically make the inducer enable the move in any of its targets. So to describe move borrowing as induction raises the issue of type selectivity, while Betza notation is typically 'type-blind'.

Main shortcoming of this system is that it does not allow for 'enemy induction'. The only case of that I was aware of was the Ultima Chameleon, however. Hence the proposal for M.

I still think that effects like immobilizing are not moves. We should also realize that Betza notation is only useful in so far it can be easily remembered what the symbols mean, or should be. Defining very specific symbols for describing rules that almost never apply would not satisfy that requirement. The x modifier is already stretching this. People would in general not understand what you mean if you say 'this piece moves as mN[xN-N] (as in Knight-relay Chess). The main reason for me to implement it is that XBetza notation serves the additional purpose of configuring the Interactive Diagram for playing a given variant, and that I wanted the latter be able to implement Scirocco and Odin's Rune Chess.