Strange. Define
a = (x == 12/5 &&
4/5 < y < 224/85 && (9 y)/56 <= z <= -(3/20) (-16 + 5 y) &&
d == -(7/30) (-9 + 5 z) && f == 1/60 (-9 y + 56 z) &&
g == 1/40 (48 - 15 y - 20 z));
b = (x == 12/5 && y == 224/85 && z == 36/85 && d == 273/170 &&
f == 0 && g == 0);
c = (x == 12/5 &&
4/5 < y <= 224/85 && (9 y)/56 <= z <= -(3/20) (-16 + 5 y) &&
d == -(7/30) (-9 + 5 z) && f == 1/60 (-9 y + 56 z) &&
g == 1/40 (48 - 15 y - 20 z));
Both
Reduce[Or[a, b] && Not[c]]
Reduce[Not@Or[a, b] && c]
give False
very quickly. I would expect the following to give True
quickly:
Reduce[Equivalent[Or[a, b], c]]
Instead, it gives a complicated expression.