pragma experimental SMTChecker; contract C { mapping (uint => uint) map; function f(uint x, uint p) public { require(x < 100); map[p] = 200; map[p] -= map[p] - x; assert(map[p] >= 0); assert(map[p] < 90); } } // ---- // Warning 6328: (197-216): CHC: Assertion violation happens here.\nCounterexample:\n\nx = 99\np = 0\n\n\nTransaction trace:\nconstructor()\nf(99, 0)