LAC-Z3-Introduction/Lecture3/snippet.py

solver = z3.Solver()

num = len(matching)
goal_steps = [[z3.Int(f'g-{n}-{t}') for t in range(num+1)] for n in range(num)] # goal number-of-match time
goal_steps_bool = [[z3.Bool(f'gb-{n}-{t}') for t in range(num+1)] for n in range(num)]
start_steps = [[z3.Int(f's-{n}-{t}') for t in range(num+1)] for n in range(num)] # start number-of-match time
start_steps_bool = [[z3.Bool(f'sb-{n}-{t}') for t in range(num+1)] for n in range(num)]

for n in range(num):
for t in range(num+1):
    solver.add(z3.Or(start_steps[n][t]==0,start_steps[n][t]==1))
    solver.add(z3.Or(goal_steps[n][t]==0,goal_steps[n][t]==1))

    # start and end always different
    solver.add(start_steps[n][t] != goal_steps[n][t])

    solver.add(goal_steps_bool[n][t] == z3.If(goal_steps[n][t]==1,True,False))
    solver.add(goal_steps[n][t] == z3.If(goal_steps_bool[n][t]==True,1,0))
    solver.add(start_steps_bool[n][t] == z3.If(start_steps[n][t]==1,True,False))
    solver.add(start_steps[n][t] == z3.If(start_steps_bool[n][t]==True,1,0))

for t in range(num+1):
	solver.add(z3.Sum([goal_steps[ni][t] for ni in range(num)]) == t) # at t=0, all goals false -> increasing

# given implicitly, s != g
# starts_at_t = [start_steps[ni][t] for ni in range(num)]
# solver.add(z3.Sum(starts_at_t) == (num-t)) # at t=0, all start

for n in range(num):
	for t in range(num+1):
    		solver.add(z3.Implies(goal_steps_bool[n][t],z3.And(goal_steps_bool[n][t+1:num+1])))

for s_pt,_,g_vec in start_intersect_triple:
	s_pt_i = find_index_init(matching,s_pt)
	g_vec_i = find_index_goal(matching,g_vec)
	conflicting_starts = []
	for t in range(num+1):
	    conflicting_starts.append(z3.Implies( goal_steps_bool[g_vec_i][t],z3.Or( [z3.Not(start_steps_bool[s_pt_i][ti]) for ti in range(t)] ) ))
	solver.assert_and_track(z3.And(conflicting_starts), f"s-i1:{s_pt_i};i2:{g_vec_i}")

for g_pt,_,g_vec in goal_intersect_triple:
	g_pt_i = find_index_goal(matching,g_pt)
	g_vec_i = find_index_goal(matching,g_vec)
	conflicting_goals = []
	for t in range(num+1):
	    conflicting_goals.append(z3.Implies( goal_steps_bool[g_pt_i][t], z3.Or([goal_steps_bool[g_vec_i][ti] for ti in range(t)]) ))
	solver.assert_and_track(z3.And(conflicting_goals),f"g-i1:{g_pt_i};i2:{g_vec_i}")


res = solver.check()
if res == z3.sat:
	print(solver.model())
else:
	core = solver.unsat_core()
	print(solver.sexpr())
	print(core)