formula for defenction chance?

[WackenOpenAir]

i know city defection depends on distance to capital, number of native citizens, units in town, culture, revolt/wltk, but i would like to have an exact formula so that i can evaluate my chances before taking a city (at high cost)

if map size and difficulty matters, i am playing deity on large map (not largest, but size 4 of 5).

[Solver]

http://apolyton.net/forums/showthrea...threadid=39825