I now have added a promotability evaluation to Scirocco that doesn't seem too idiotic. The idea is that the promotion gain of each piece is multiplied with the estimated probability the piece will promote. Sliders then get 90% of that value added to their piece value, while for leapers it ranges from 20-90% depending on how far they are from the zone. (Measured in the difficulty to go there, considering the size of their leap, but also the number of forward moves with such a leap; a Dababba would be discounted more than an Alfil in the same location.)
The probability estimate assumes there is a certain minimum army strength required to defend the zone, and that you first have to reduce the opponent army to that level by equal trading before you can promote. What you have left at that point will promote.
This doesn't account for the fact that some pieces gain more on promotion than others, and that you will try to selectively preserve those in the unpromoted-trading phase. Because the opponent of course will try to preferentially trade your good promoters away, I am not usre how successful such a strategy can be on average.
Another subtlety is that there are fast promoters (sliders), which will start promoting as soon as the entire zone cannot be defended, and slow promoters (leapers), who will take some time to get there even if unobstructed, and can much easier be defended against because of their low mobilty. You would only have to defend the entrance of the zone, and can often even prevent they reach the zone by meeting them far before they get there with your own leapers.
In a contest where one side has fast promoters and the other slow ones, of equal total value and gaining equally on promotion, the player with the fast promoters would promote those before the slow ones can promote, and then try to trade those according to their increased value for the yet unpromoted opponent pieces, leaving him a surplus after the slow ones are annihilated. This is currently not yet accounted for. In Scirocco it might not be that important, as there are very few sliders in the initial setup there. (And the Scirocco's don't have such a strong promotion.) But it would be for Chu Shogi.
I now have added a promotability evaluation to Scirocco that doesn't seem too idiotic. The idea is that the promotion gain of each piece is multiplied with the estimated probability the piece will promote. Sliders then get 90% of that value added to their piece value, while for leapers it ranges from 20-90% depending on how far they are from the zone. (Measured in the difficulty to go there, considering the size of their leap, but also the number of forward moves with such a leap; a Dababba would be discounted more than an Alfil in the same location.)
The probability estimate assumes there is a certain minimum army strength required to defend the zone, and that you first have to reduce the opponent army to that level by equal trading before you can promote. What you have left at that point will promote.
This doesn't account for the fact that some pieces gain more on promotion than others, and that you will try to selectively preserve those in the unpromoted-trading phase. Because the opponent of course will try to preferentially trade your good promoters away, I am not usre how successful such a strategy can be on average.
Another subtlety is that there are fast promoters (sliders), which will start promoting as soon as the entire zone cannot be defended, and slow promoters (leapers), who will take some time to get there even if unobstructed, and can much easier be defended against because of their low mobilty. You would only have to defend the entrance of the zone, and can often even prevent they reach the zone by meeting them far before they get there with your own leapers.
In a contest where one side has fast promoters and the other slow ones, of equal total value and gaining equally on promotion, the player with the fast promoters would promote those before the slow ones can promote, and then try to trade those according to their increased value for the yet unpromoted opponent pieces, leaving him a surplus after the slow ones are annihilated. This is currently not yet accounted for. In Scirocco it might not be that important, as there are very few sliders in the initial setup there. (And the Scirocco's don't have such a strong promotion.) But it would be for Chu Shogi.