示例#1
0
    def test__get_derivations__3(self):
        p = Program.parse("""
            a <- b, c. 
            b <- d, e. 
            b <- c. 
            c <- f, g. 
            d <- h. 
            e. 
            f. 
            g. 
            h.
        """)
        i = Interpreter(p)
        expected = {
            Derivation([
                Rule.parse('b <- c.'),
                Rule.parse('c <- f, g.'),
                Rule.parse('f.'),
                Rule.parse('g.')
            ], i),
            Derivation([
                Rule.parse('b <- d, e.'),
                Rule.parse('d <- h.'),
                Rule.parse('h.'),
                Rule.parse('e.')
            ], i),
        }
        result = i.get_derivations(Literal.parse('b'))

        assert_that(result).is_equal_to(expected)
示例#2
0
    def test__get_derivations__flies_tina__defeasibly(self):
        p = Program.parse("""
            bird(X) <- chicken(X).
            bird(X) <- penguin(X).
            ~flies(X) <- penguin(X).
            chicken(tina).
            penguin(tweety).
            scared(tina).
            flies(X) -< bird(X).
            flies(X) -< chicken(X), scared(X).
            nests_in_trees(X) -< flies(X).
            ~flies(X) -< chicken(X).
        """)
        i = Interpreter(p)
        expected = {
            Derivation([
                Rule.parse('flies(tina) -< chicken(tina), scared(tina).'),
                Rule.parse('chicken(tina).'),
                Rule.parse('scared(tina).')
            ], i),
            Derivation([
                Rule.parse('flies(tina) -< bird(tina).'),
                Rule.parse('bird(tina) <- chicken(tina).'),
                Rule.parse('chicken(tina).')
            ], i),
        }
        result = i.get_derivations(Literal.parse('flies(tina)'),
                                   RuleType.DEFEASIBLE)

        assert_that(result).is_equal_to(expected)
示例#3
0
    def test__get_derivations__not_flies_tina__strictly(self):
        p = Program.parse("""
            bird(X) <- chicken(X).
            bird(X) <- penguin(X).
            ~flies(X) <- penguin(X).
            chicken(tina).
            penguin(tweety).
            scared(tina).
            flies(X) -< bird(X).
            flies(X) -< chicken(X), scared(X).
            nests_in_trees(X) -< flies(X).
            ~flies(X) -< chicken(X).
        """)
        i = Interpreter(p)
        expected = set()
        result = i.get_derivations(Literal.parse('~flies(tina)'),
                                   RuleType.STRICT)

        assert_that(result).is_equal_to(expected)