Animals example (animals.sc1).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
After the `======' in this file is a session of
Progol running in batch mode (non-interactively).
The file animals.sc2 contains an interactive session for the
animals example.

Below Progol reads in the file animals.pl. It notes all
mode declarations and adds background knowledge and positive
and negative examples to its clause base. Have a look at the file
animals.pl. A mode declaration is a query aimed at the Prolog
interpreter within Progol. Prolog queries have a `:-' at the
beginning and a `?' at the end to differentiate them from
from aserted statements. Thus

  :- modeb(1,has_milk(+animal))?

is a mode declaration describing the form of a literal which can be
used in a Progol hypothesised clause (see more about mode declarations
below).

A positive example is a statement such as 

  class(dog,mammal).

A negative example is a statement such as

  :- class(trout,mammal).

Background knowledge is described as arbitrary pieces of Prolog
code. For instance,

  has_eggs(trout).

is a statement in the background knowledge.

Progol generalises any predicates associated with `modeh'
(head mode) declarations. In this case, the predicate class/2.
The statement

  :- modeh(1,class(+animal,#class))? 

says that generalisations must all have the form

  class(A,#) :- ...

where A is an input variable of type animal/1 and # is a constant
of type class/1. The bodies of generalisations will be constructed
using `modeb' (body mode) declarations. For instance the declaration

  :- modeb(1,has_milk(+animal))?

allows the generalisation

  class(A,mammal) :- has_milk(A).

In the following Progol first learns constraints such as 

  :- class(A,mammal), class(A,fish).

which says the no mammal is a fish and conversely no fish is a mammal.
This clause is stored within Progol as

  false :- class(A,mammal), class(A,fish).

This is a generalisation of the negative example

  :- class(trout,mammal).

Following this, general rules are learned for distingishing the
class of animals. For instance,

  class(A,bird) :- has_covering(A,feathers).

Progol finishes by printing the new definition of class/2.
Note that snakes are treated as exceptions since all other reptiles
have 4 legs.

=============


scye.comlab_{{24}}? progol animals
CProgol Version 4.1

[:- set(c,3)? - Time taken 0.00s]
[:- modeh(1,class(+animal,#class))? - Time taken 0.00s]
[:- modeb(1,has_milk(+animal))? - Time taken 0.00s]
[:- modeb(1,has_gills(+animal))? - Time taken 0.00s]
[:- modeb(1,has_covering(+animal,#covering))? - Time taken 0.00s]
[:- modeb(1,has_legs(+animal,#nat))? - Time taken 0.00s]
[:- modeb(1,homeothermic(+animal))? - Time taken 0.00s]
[:- modeb(1,has_eggs(+animal))? - Time taken 0.00s]
[:- modeb(100,habitat(+animal,#habitat))? - Time taken 0.00s]
[:- modeh(1,false)? - Time taken 0.00s]
[:- modeb(1,class(+animal,#class))? - Time taken 0.00s]
[Generalising :- class(trout,mammal).]
[Most specific clause is]
:- class(A,mammal), class(A,fish), has_gills(A), has_covering(A,
	scales), has_legs(A,0), has_eggs(A), habitat(A,water).
[C:40,42,1,0 :- class(A,mammal).]
[C:5,7,0,0 :- class(A,mammal), class(A,fish).]
[C:39,42,1,0 :- class(A,mammal), has_legs(A,0).]
[C:39,42,1,0 :- class(A,mammal), has_eggs(A).]
[C:39,42,1,0 :- class(A,mammal), habitat(A,water).]
[C:38,42,1,0 :- class(A,mammal), has_eggs(A), habitat(A,water).]
[C:38,42,1,0 :- class(A,mammal), has_legs(A,0), habitat(A,water).]
[7 explored search nodes]
[f=5,p=7,n=0,h=0]
[Result of search is]
:- class(A,mammal), class(A,fish).
[7 redundant clauses retracted]

[Generalising :- class(lizard,mammal).]
[Most specific clause is]
:- class(A,mammal), class(A,reptile), has_covering(A,scales),
	has_legs(A,4), has_eggs(A), habitat(A,land).
[C:34,36,1,0 :- class(A,mammal).]
[C:6,8,0,0 :- class(A,mammal), class(A,reptile).]
[C:33,36,1,0 :- class(A,mammal), has_legs(A,4).]
[C:33,36,1,0 :- class(A,mammal), has_eggs(A).]
[C:33,36,1,0 :- class(A,mammal), habitat(A,land).]
[C:32,36,1,0 :- class(A,mammal), has_legs(A,4), habitat(A,land).]
[6 explored search nodes]
[f=6,p=8,n=0,h=0]
[Result of search is]
:- class(A,mammal), class(A,reptile).
[8 redundant clauses retracted]

[Generalising :- class(eagle,mammal).]
[Most specific clause is]
:- class(A,mammal), class(A,bird), has_covering(A,feathers), 
	has_legs(A,2), homeothermic(A), has_eggs(A), habitat(A,
	land), habitat(A,air).
[C:27,29,1,0 :- class(A,mammal).]
[C:5,7,0,0 :- class(A,mammal), class(A,bird).]
[C:26,29,1,0 :- class(A,mammal), has_legs(A,2).]
[C:26,29,1,0 :- class(A,mammal), homeothermic(A).]
[C:26,29,1,0 :- class(A,mammal), has_eggs(A).]
[C:26,29,1,0 :- class(A,mammal), habitat(A,land).]
[C:26,29,1,0 :- class(A,mammal), habitat(A,air).]
[C:25,29,1,0 :- class(A,mammal), has_legs(A,2), homeothermic(A).]
[C:25,29,1,0 :- class(A,mammal), has_legs(A,2), has_eggs(A).]
[C:25,29,1,0 :- class(A,mammal), has_legs(A,2), habitat(A,air).]
[C:25,29,1,0 :- class(A,mammal), homeothermic(A), has_eggs(A).]
[C:25,29,1,0 :- class(A,mammal), homeothermic(A), habitat(A,land).]
[C:25,29,1,0 :- class(A,mammal), homeothermic(A), habitat(A,air).]
[13 explored search nodes]
[f=5,p=7,n=0,h=0]
[Result of search is]
:- class(A,mammal), class(A,bird).
[7 redundant clauses retracted]

[Generalising :- class(lizard,fish).]
[Most specific clause is]
:- class(A,fish), class(A,reptile), has_covering(A,scales), has_legs(A,
	4), has_eggs(A), habitat(A,land).
[C:21,23,1,0 :- class(A,fish).]
[C:5,7,0,0 :- class(A,fish), class(A,reptile).]
[C:20,23,1,0 :- class(A,fish), has_covering(A,scales).]
[C:20,23,1,0 :- class(A,fish), has_eggs(A).]
[C:19,23,1,0 :- class(A,fish), has_covering(A,scales), has_eggs(A).]
[5 explored search nodes]
[f=5,p=7,n=0,h=0]
[Result of search is]
:- class(A,fish), class(A,reptile).
[7 redundant clauses retracted]

[Generalising :- class(eagle,fish).]
[Most specific clause is]
:- class(A,fish), class(A,bird), has_covering(A,feathers), has_legs(A,
	2), homeothermic(A), has_eggs(A), habitat(A,land), habitat(A,
	air).
[C:15,17,1,0 :- class(A,fish).]
[C:4,6,0,0 :- class(A,fish), class(A,bird).]
[C:14,17,1,0 :- class(A,fish), has_eggs(A).]
[3 explored search nodes]
[f=4,p=6,n=0,h=0]
[Result of search is]
:- class(A,fish), class(A,bird).
[6 redundant clauses retracted]

[Generalising :- class(eagle,reptile).]
[Most specific clause is]
:- class(A,reptile), class(A,bird), has_covering(A,feathers),
	has_legs(A,2), homeothermic(A), has_eggs(A), habitat(A,
	land), habitat(A,air).
[C:10,12,1,0 :- class(A,reptile).]
[C:5,7,0,0 :- class(A,reptile), class(A,bird).]
[C:9,12,1,0 :- class(A,reptile), has_eggs(A).]
[C:9,12,1,0 :- class(A,reptile), habitat(A,land).]
[C:8,12,1,0 :- class(A,reptile), has_eggs(A), habitat(A,land).]
[5 explored search nodes]
[f=5,p=7,n=0,h=0]
[Result of search is]
:- class(A,reptile), class(A,bird).
[7 redundant clauses retracted]

:- class(A,mammal), class(A,fish).
:- class(A,mammal), class(A,reptile).
:- class(A,mammal), class(A,bird).
:- class(A,fish), class(A,reptile).
:- class(A,fish), class(A,bird).
:- class(A,reptile), class(A,bird).
[Total number of clauses = 6]

[Time taken 1.228s]
[Generalising class(dog,mammal).]
[Most specific clause is]
class(A,mammal) :- has_milk(A), has_covering(A,hair), has_legs(A,
	4), homeothermic(A), habitat(A,land).
[C:1,4,3,0 class(A,mammal).]
[C:3,4,0,0 class(A,mammal) :- has_milk(A).]
[2 explored search nodes]
[f=3,p=4,n=0,h=0]
[Result of search is]
class(A,mammal) :- has_milk(A).
[4 redundant clauses retracted]

[Generalising class(trout,fish).]
[Most specific clause is]
class(A,fish) :- has_gills(A), has_covering(A,scales), has_legs(A,
	0), has_eggs(A), habitat(A,water).
[C:1,4,3,0 class(A,fish).]
[C:3,4,0,0 class(A,fish) :- has_gills(A).]
[2 explored search nodes]
[f=3,p=4,n=0,h=0]
[Result of search is]
class(A,fish) :- has_gills(A).
[4 redundant clauses retracted]

[Generalising class(lizard,reptile).]
[Most specific clause is]
class(A,reptile) :- has_covering(A,scales), has_legs(A,4), has_eggs(A),
	habitat(A,land).
[C:2,5,3,0 class(A,reptile).]
[C:3,5,1,0 class(A,reptile) :- has_covering(A,scales).]
[C:2,4,0,0 class(A,reptile) :- has_covering(A,scales), has_legs(A,4).]
[C:2,5,1,0 class(A,reptile) :- has_covering(A,scales), has_eggs(A).]
[C:2,4,1,0 class(A,reptile) :- has_legs(A,4).]
[C:1,5,3,0 class(A,reptile) :- has_eggs(A).]
[C:1,4,2,0 class(A,reptile) :- habitat(A,land).]
[7 explored search nodes]
[f=2,p=4,n=0,h=0]
[Result of search is]
class(A,reptile) :- has_covering(A,scales), has_legs(A,4).
[4 redundant clauses retracted]

[Generalising class(snake,reptile).]
[Most specific clause is]
class(A,reptile) :- has_covering(A,scales), has_legs(A,0), has_eggs(A),
	habitat(A,land).
[C:-1,2,3,0 class(A,reptile).]
[C:0,2,1,0 class(A,reptile) :- has_covering(A,scales).]
[2 explored search nodes]
[f=1,p=7,n=6,h=0]
[No compression]

[Generalising class(eagle,bird).]
[Most specific clause is]
class(A,bird) :- has_covering(A,feathers), has_legs(A,2), homeothermic(A),
	has_eggs(A), habitat(A,land), habitat(A,air).
[C:0,3,3,0 class(A,bird).]
[C:2,3,0,0 class(A,bird) :- has_covering(A,feathers).]
[2 explored search nodes]
[f=2,p=3,n=0,h=0]
[Result of search is]
class(A,bird) :- has_covering(A,feathers).
[3 redundant clauses retracted]

class(snake,reptile).
class(A,mammal) :- has_milk(A).
class(A,fish) :- has_gills(A).
class(A,bird) :- has_covering(A,feathers).
class(A,reptile) :- has_covering(A,scales), has_legs(A,4).
[Total number of clauses = 5]

[Time taken 0.332s]