@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 testHashCode() {
Var a = new Var("a");
Var b = new Var("b");
Formula f = a.and(b);
Formula g = a.and(b);
assertTrue(f.hashCode() == g.hashCode()); // two distinct instances
Formula h = b.and(a);
assertFalse(f.hashCode() == h.hashCode()); // logically equivalent but different hash codes
}
@Test
public void testEquals() {
Var a = new Var("a");
Var b = new Var("b");
Formula f = a.and(b);
Formula g = a.and(b);
assertFalse(f == g); // two distinct instances
assertTrue(f.equals(g)); // objects equal
Formula h = b.and(a);
assertFalse(f.equals(h)); // logically equivalent but objects not equal
}
@Test
public void testToString() {
Formula emptyFormula = new Formula();
assertTrue(emptyFormula.toString().equals(StringUtils.EMPTY));
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 and b) or (c and d)".equals(f.toString()));
f = (a.not().or(b)).and(c);
assertTrue("(!a or b) and c".equals(f.toString()));
}
@Test
public void testCreateFromConjunctionOfLiterals() {
Var a = new Var("a");
Var b = new Var("b");
Phrase phrase = new Phrase(a.and(b));
assertTrue("a and b".equals(phrase.toString()));
}
@Test
public void testAnd() {
Var a = new Var("a");
Var b = new Var("b");
Formula f = (a.and(b));
assertTrue("a and b".equals(f.toString()));
}
@Test
public void testGetRight() {
Var a = new Var("a");
Var b = new Var("b");
Formula f = (a.and(b));
assertTrue(f.getRight().equals(b));
}
@Test
public void testGetOp() {
Var a = new Var("a");
Var b = new Var("b");
Formula f = (a.and(b));
assertTrue(f.getOp().equals(Formula.BOP.AND));
}
@Test
public void testIsLeaf() {
Var a = new Var("a");
Var b = new Var("b");
Formula f = (a.and(b));
assertFalse(f.isLeaf());
assertTrue(f.getLeft().isLeaf() == true && f.getRight().isLeaf() == true);
}
@Test
public void testIsAtomic() {
Var a = new Var("a");
Var b = new Var("b");
assertTrue(a.isAtomic()); // a literal is atomic
assertTrue(a.not().isAtomic()); // a literal and its negation is atomic
Formula f = (a.and(b));
assertFalse(f.isAtomic());
assertTrue(f.getLeft().isAtomic() == true && f.getRight().isAtomic() == true);
}
@Test
public void testIsPhrase() {
Var a = new Var("a");
Var b = new Var("b");
Var c = new Var("c");
assertTrue(a.isPhrase());
assertTrue(b.isPhrase());
assertTrue(c.isPhrase());
// if a and b are both phrases, then so is (a and b)
Formula f = a.and(b);
assertTrue(f.isPhrase());
// if f is a phrase and c is a phrase, then so is (f and c)
assertTrue(f.and(c).isPhrase());
assertTrue(c.and(f).isPhrase());
Formula g = a.or(b);
assertFalse(g.isPhrase());
assertFalse(g.and(c).isPhrase());
assertFalse(c.and(g).isPhrase());
}
@Test
public void testIsClause() {
Var a = new Var("a");
Var b = new Var("b");
Var c = new Var("c");
assertTrue(a.isClause());
assertTrue(b.isClause());
assertTrue(c.isClause());
// if a and b are both clauses, then so is (a or b)
Formula f = a.or(b);
assertTrue(f.isClause());
// if f is a literals and c is a literals, then so is (f or c)
assertTrue(f.or(c).isClause());
assertTrue(c.or(f).isClause());
Formula g = a.and(b);
assertFalse(g.isClause());
assertFalse(g.or(c).isClause());
assertFalse(c.or(g).isClause());
}
@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()))));
}