@Test
public void testCreateFromNegationOfLiteral() {
Var a = new Var("a");
Phrase phrase = new Phrase(a.not());
assertTrue("!a".equals(phrase.toString()));
a = new Var(1);
phrase = new Phrase(a.not());
assertTrue("!1".equals(phrase.toString()));
a = new Var(true);
phrase = new Phrase(a.not());
assertTrue("!true".equals(phrase.toString()));
}
@Test
public void testNot() {
Var a = new Var("a");
Formula f = (a.not());
assertTrue("!a".equals(f.toString()));
}
@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 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 testIsPossiblySatisfiedBy() throws ContradictionException, TimeoutException {
Var P = new Var("P");
Var Q = new Var("Q");
Var R = new Var("R");
Formula f = Formula.newInstanceforSAT((P.or(Q)).and(P.not().or(R))); // (P or Q) and (~P or R)
// Possible assignments
// ~P ~Q ~R
// ~P ~Q R
// ~P Q ~R (solution)
// ~P Q R (solution
// P ~Q ~R
// P ~Q R (solution)
// P Q ~R
// P Q R (solution)
BidiMap map = f.getVariableMap();
assertTrue(map.get(1).equals("P"));
assertTrue(map.get(2).equals("Q"));
assertTrue(map.get(3).equals("R"));
// The following partial models should pass
assertTrue(f.isPossiblySatisfiedBy(new Model(new int[] {})));
assertTrue(f.isPossiblySatisfiedBy(new Model(new int[] {-1})));
assertTrue(f.isPossiblySatisfiedBy(new Model(new int[] {1})));
assertTrue(f.isPossiblySatisfiedBy(new Model(new int[] {-1, 2})));
assertTrue(f.isPossiblySatisfiedBy(new Model(new int[] {1, 3})));
// These partial models should not
assertFalse(f.isPossiblySatisfiedBy(new Model(new int[] {-2, -3})));
// Complete models, by definition, should satisfy (if solutions)
assertFalse(f.isPossiblySatisfiedBy(new Model(new int[] {-1, -2, -3})));
assertFalse(f.isPossiblySatisfiedBy(new Model(new int[] {-1, -2, 3})));
assertTrue(f.isPossiblySatisfiedBy(new Model(new int[] {-1, 2, -3})));
assertTrue(f.isPossiblySatisfiedBy(new Model(new int[] {-1, 2, 3})));
assertFalse(f.isPossiblySatisfiedBy(new Model(new int[] {1, -2, -3})));
assertTrue(f.isPossiblySatisfiedBy(new Model(new int[] {1, -2, 3})));
assertFalse(f.isPossiblySatisfiedBy(new Model(new int[] {1, 2, -3})));
assertTrue(f.isPossiblySatisfiedBy(new Model(new int[] {1, 2, 3})));
}
@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()))));
}