public void MakeNot()
{
var obdd = new OBDD();
var a = obdd.MakeLiteral(0);
var b = obdd.MakeLiteral(1);
Assert.IsNotNull(a);
Assert.IsNotNull(b);
Assert.AreNotEqual(a, b);
var na = obdd.MakeNot(a);
var nb = obdd.MakeNot(b);
Assert.IsNotNull(na);
Assert.IsNotNull(nb);
Assert.AreNotEqual(na, nb);
Assert.AreNotEqual(a, na);
Assert.AreNotEqual(b, nb);
var nna = obdd.MakeNot(na);
var nnb = obdd.MakeNot(nb);
Assert.IsNotNull(nna);
Assert.IsNotNull(nnb);
Assert.AreNotEqual(nna, nnb);
// double negation cancels out
Assert.AreEqual(a, nna);
Assert.AreEqual(b, nnb);
}
public void Example()
{
// f(a,b,c) = (!a & !b & !c) | (a & b) | (b & c)
var obdd = new OBDD();
var a = obdd.MakeNode(0, BDDNode.True, BDDNode.False);
var b = obdd.MakeNode(1, BDDNode.True, BDDNode.False);
var c = obdd.MakeNode(2, BDDNode.True, BDDNode.False);
var na = obdd.MakeNot(a);
var nb = obdd.MakeNot(b);
var nc = obdd.MakeNot(c);
var tmpAnd = obdd.MakeAnd(na, nb);
var and1 = obdd.MakeAnd(tmpAnd, nc);
var and2 = obdd.MakeAnd(a, b);
var and3 = obdd.MakeAnd(b, c);
var tmpOr = obdd.MakeOr(and1, and2);
var or = obdd.MakeOr(tmpOr, and3);
var root = or;
using (var writer = new StringWriter())
{
root.ExportToGraphviz(writer);
Debug.Log(writer);
}
}
private static BDDNode AddTransition(OBDD obdd, BDDNode node, int index, int numBits, int offset)
{
for (int i = 0; i < numBits; i++)
{
int literal = i * 2 + offset;
var variable = obdd.MakeLiteral(literal);
bool hasBit = (index & (1 << i)) != 0;
if (!hasBit)
{
variable = obdd.MakeNot(variable);
}
node = obdd.MakeAnd(node, variable);
}
return(node);
}