@Test
public void testToCNF() {
Var a = new Var("a");
Var b = new Var("b");
Var c = new Var("c");
Var d = new Var("d");
Formula f = (a.and(b)).or(c.and(d));
assertTrue("(a or c) and (b or c) and (a or d) and (b or d)".equals(f.toCNF().toString()));
f = (a.and(b)).or(c).or(d);
assertTrue("(a or c or d) and (b or c or d)".equals(f.toCNF().toString()));
f = ((a.and(b)).or(c).or(d)).not();
assertTrue("(!a or !b) and !c and !d".equals(f.toCNF().toString()));
f = (a).not().not().not().not().not().not();
assertTrue("a".equals(f.toCNF().toString()));
f = (a).not().not().not().not().not();
assertTrue("!a".equals(f.toCNF().toString()));
f = ((a).and(b)).or((a).not().and(c)).or(((b).not()).and((c).not()));
assertTrue(
"(a or !a or !b) and (b or !a or !b) and (a or c or !b) and (b or c or !b) and (a or !a or !c) and (b or !a or !c) and (a or c or !c) and (b or c or !c)"
.equals(f.toCNF().toString()));
}
@Test
public void testToCNFClauses() {
Var a = new Var("a");
Var b = new Var("b");
Var c = new Var("c");
Var d = new Var("d");
Formula f = a.or(b).or(c).or(d);
assertTrue("a or b or c or d".equals(f.toCNF().toString()));
List<Clause> clauses = f.toCNFClauses();
assertTrue(clauses.size() == 1);
assertTrue("a or b or c or d".equals(clauses.get(0).toString()));
f = (a.and(b)).or(c.and(d));
assertTrue("(a or c) and (b or c) and (a or d) and (b or d)".equals(f.toCNF().toString()));
clauses = f.toCNFClauses();
assertTrue(clauses.size() == 4);
assertTrue(clauses.contains(new Clause(a.or(c))));
assertTrue(clauses.contains(new Clause(b.or(c))));
assertTrue(clauses.contains(new Clause(a.or(d))));
assertTrue(clauses.contains(new Clause(b.or(d))));
f = (a.and(b)).or(c).or(d);
assertTrue("(a or c or d) and (b or c or d)".equals(f.toCNF().toString()));
clauses = f.toCNFClauses();
assertTrue(clauses.size() == 2);
assertTrue(clauses.contains(new Clause(a.or(c).or(d))));
assertTrue(clauses.contains(new Clause(b.or(c).or(d))));
f = ((a.and(b)).or(c).or(d)).not();
assertTrue("(!a or !b) and !c and !d".equals(f.toCNF().toString()));
clauses = f.toCNFClauses();
assertTrue(clauses.size() == 3);
assertTrue(clauses.contains(new Clause((a.not()).or(b.not()))));
assertTrue(clauses.contains(new Clause(c.not())));
assertTrue(clauses.contains(new Clause(d.not())));
f = (a).not().not().not().not().not().not();
assertTrue("a".equals(f.toCNF().toString()));
clauses = f.toCNFClauses();
assertTrue(clauses.size() == 1);
assertTrue(clauses.contains(new Clause(a)));
f = (a).not().not().not().not().not();
assertTrue("!a".equals(f.toCNF().toString()));
clauses = f.toCNFClauses();
assertTrue(clauses.size() == 1);
assertTrue(clauses.contains(new Clause(a.not())));
f = ((a).and(b)).or((a).not().and(c)).or(((b).not()).and((c).not()));
assertTrue(
"(a or !a or !b) and (b or !a or !b) and (a or c or !b) and (b or c or !b) and (a or !a or !c) and (b or !a or !c) and (a or c or !c) and (b or c or !c)"
.equals(f.toCNF().toString()));
clauses = f.toCNFClauses();
assertTrue(clauses.size() == 8);
assertTrue(clauses.contains(new Clause(a.or(a.not()).or(b.not()))));
assertTrue(clauses.contains(new Clause(b.or(a.not()).or(b.not()))));
assertTrue(clauses.contains(new Clause(a.or(c).or(b.not()))));
assertTrue(clauses.contains(new Clause(b.or(c).or(b.not()))));
assertTrue(clauses.contains(new Clause(a.or(a.not()).or(c.not()))));
assertTrue(clauses.contains(new Clause(b.or(a.not()).or(c.not()))));
assertTrue(clauses.contains(new Clause(a.or(c).or(c.not()))));
assertTrue(clauses.contains(new Clause(b.or(c).or(c.not()))));
}
@Test
public void testToCNF_empty() {
Formula f = new Formula();
assertTrue(f.toCNF().isEmpty());
}