func BenchmarkBuilder(b *testing.B) {
b.ReportAllocs()
for i := 0; i < b.N; i++ {
b := NewBuilder()
lit := make([]*Robdd, 10)
for j := range lit {
lit[j] = b.NewLiteral(boolean.Var(j))
}
d1 := b.Apply(OpXor, lit[0], lit[1])
d2 := b.Apply(OpOr, lit[2], lit[3])
d3 := b.Apply(OpAnd, lit[4], lit[5])
d4 := b.Apply(OpIff, lit[6], lit[7])
d5 := b.Apply(OpImplies, lit[8], lit[9])
d1 = b.Apply(OpXor, d1, d3)
d2 = b.Apply(OpAnd, d2, d5)
d3 = b.Apply(OpOr, d1, d4)
d4 = b.Apply(OpImplies, d2, d3)
d5 = b.Apply(OpIff, b.NewLiteral(boolean.Var(10)), d4)
}
}
func TestSAT(t *testing.T) {
b := NewBuilder()
unsat := b.Constant(false)
check := func() {
if assign := unsat.AnySat(); assign != nil {
t.Errorf("AnySat returned %v for unsatisfiable formula",
assign)
}
if n := unsat.Size(); n != 1 {
t.Errorf("unsatisfiable formula has %d nodes, expected one", n)
}
}
check()
unsat = b.Apply(OpAnd, unsat, b.Constant(true))
unsat = b.Apply(OpAnd, unsat, b.NewLiteral(boolean.Var(1)))
unsat = b.Apply(OpAnd, unsat, unsat)
}
func TestBDD(t *testing.T) {
b := NewBuilder()
// Construct the formula (0 and 1) or (2 and (1 or 0)).
var v []*Robdd
for i := 0; i < 4; i++ {
v = append(v, b.NewLiteral(boolean.Var(i)))
}
f := b.Apply(OpAnd, v[0], v[1])
g := b.Apply(OpAnd, v[2], b.Apply(OpOr, v[1], v[0]))
h := b.Apply(OpOr, f, g)
_ = h
for _, c := range []struct {
bdd *Robdd
assign map[boolean.Var]bool
}{
{f, map[boolean.Var]bool{0: false, 1: false}},
{g, map[boolean.Var]bool{0: true, 1: true, 2: false}},
{h, map[boolean.Var]bool{0: false, 1: false, 2: true}},
} {
if checkSat(c.bdd.root, c.assign) {
t.Error("construction error")
}
}
for _, bdd := range []*Robdd{f, g, h} {
if assign := bdd.AnySat(); !checkSat(bdd.root, assign) {
t.Errorf("not a SAT solution: %v", assign)
}
}
r := h.Eval(func(v boolean.Var) bool {
return [...]bool{true, false, true}[int(v)]
})
if !r {
t.Error("expected true, got false from Eval")
}
}