Introduced ordering at model level...

generate_model.py

@@ -46,7 +46,6 @@ def only_rules_with(rules: Set[Rule], operation: Operation) -> Set[Rule]:
     return result_rules
 
 
-
 def possible_interpretations(
         logic: Logic, carrier_set: Set[ModelValue],
         designated_values: Set[ModelValue]):
@@ -88,10 +87,25 @@ def possible_interpretations(
         yield interpretation
 
 def generate_model(logic: Logic, number_elements: int, num_solutions: int = -1, print_model=False):
+    assert number_elements > 0
     carrier_set = {
         ModelValue("a" + str(i)) for i in range(number_elements)
     }
 
+    ordering = set()
+
+    # a(0) is less than all other elements
+    a0 = ModelValue("a0")
+    for v in carrier_set:
+        if v != a0:
+            ordering.add(a0 < v)
+
+    # Every other element is less than a(n - 1)
+    an = ModelValue(f"a{number_elements-1}")
+    for v in carrier_set:
+        if an != v:
+            ordering.add(v < an)
+
     possible_designated_values = possible_designations(carrier_set)
 
     satisfied_models = []
@@ -102,7 +116,7 @@ def generate_model(logic: Logic, number_elements: int, num_solutions: int = -1,
 
         for interpretation in possible_interps:
             is_valid = True
-            model = Model(carrier_set, set(interpretation.values()), designated_values)
+            model = Model(carrier_set, set(interpretation.values()), designated_values, ordering)
             # Iteratively test possible interpretations
             # by adding one axiom at a time
             for rule in logic.rules:

model.py

@@ -6,7 +6,7 @@ from logic import (
 PropositionalVariable, get_propostional_variables, Logic, Term,
 Operation
 )
-from typing import Set, List, Dict, Tuple
+from typing import Set, List, Dict, Tuple, Optional
 from itertools import product
 from functools import lru_cache
 
@@ -27,6 +27,9 @@ class ModelValue:
         return self.hashed_value
     def __eq__(self, other):
         return isinstance(other, ModelValue) and self.name == other.name
+    def __lt__(self, other):
+        assert isinstance(other, ModelValue)
+        return ModelOrderConstraint(self, other)
 
 
 class ModelFunction:
@@ -58,17 +61,32 @@ class ModelFunction:
     # def __eq__(self, other):
     #     return isinstance(other, ModelFunction) and self.name == other.name and self.arity == other.arity
 
+class ModelOrderConstraint:
+    # a < b
+    def __init__(self, a: ModelValue, b: ModelValue):
+        self.a = a
+        self.b = b
+    def __hash__(self):
+        return hash(self.a) * hash(self.b)
+    def __eq__(self, other):
+        return isinstance(other, ModelOrderConstraint) and \
+            self.a == other.a and self.b == other.b
+
 class Model:
     def __init__(
             self,
             carrier_set: Set[ModelValue],
             logical_operations: Set[ModelFunction],
-            designated_values: Set[ModelValue]
+            designated_values: Set[ModelValue],
+            ordering: Optional[Set[ModelOrderConstraint]] = None
     ):
         assert designated_values <= carrier_set
         self.carrier_set = carrier_set
         self.logical_operations = logical_operations
         self.designated_values = designated_values
+        self.ordering = ordering  if ordering is not None else set()
+        # TODO: Make sure ordering is "valid"
+        # That is: transitive, etc.
 
     def __str__(self):
         result = f"""Carrier Set: {set_to_str(self.carrier_set)}
@@ -116,20 +134,33 @@ def satisfiable(logic: Logic, model: Model, interpretation: Dict[Operation, Mode
     pvars = tuple(get_propostional_variables(tuple(logic.rules)))
     mappings = all_model_valuations_cached(pvars, tuple(model.carrier_set))
 
+    """
+    TODO: Make sure that ordering for conjunction and disjunction
+    at the model function level.
+    """
+
     for mapping in mappings:
         for rule in logic.rules:
             premise_met = True
+            premise_ts = set()
             for premise in rule.premises:
-                t = evaluate_term(premise, mapping, interpretation)
+                premise_t = evaluate_term(premise, mapping, interpretation)
-                if t not in model.designated_values:
+                if premise_t not in model.designated_values:
                     premise_met = False
                     break
+                premise_ts.add(premise_t)
 
             if not premise_met:
                 continue
 
-            t = evaluate_term(rule.conclusion, mapping, interpretation)
+            consequent_t = evaluate_term(rule.conclusion, mapping, interpretation)
-            if t not in model.designated_values:
+
+            if consequent_t not in model.designated_values:
+                return False
+
+            # Make sure ordering constraint is met
+            for premise_t in premise_ts:
+                if consequent_t < premise_t in model.ordering:
                     return False
 
     return True