Raise TypeError if Polyhedron.widen() is called on a non-polyhedral argument

[linpy.git] / linpy / polyhedra.py

diff --git a/linpy/polyhedra.py b/linpy/polyhedra.py
index 8426d32..e5e2523 100644 (file)
--- a/linpy/polyhedra.py
+++ b/linpy/polyhedra.py
@@ -173,9 +173,12 @@ class Polyhedron(Domain):
     def widen(self, other):
         """
         Compute the standard widening of two polyhedra, à la Halbwachs.
+
+        In its current implementation, this method is slow and should not be
+        used on large polyhedra.
         """
         if not isinstance(other, Polyhedron):
-            raise ValueError('argument must be a Polyhedron instance')
+            raise TypeError('argument must be a Polyhedron instance')
         inequalities1 = self._asinequalities()
         inequalities2 = other._asinequalities()
         inequalities = []
@@ -303,8 +306,6 @@ class EmptyType(Polyhedron):
     The empty polyhedron, whose set of constraints is not satisfiable.
     """
 
-    __slots__ = Polyhedron.__slots__
-
     def __new__(cls):
         self = object().__new__(cls)
         self._equalities = (Rational(1),)
@@ -333,8 +334,6 @@ class UniverseType(Polyhedron):
     i.e. is empty.
     """
 
-    __slots__ = Polyhedron.__slots__
-
     def __new__(cls):
         self = object().__new__(cls)
         self._equalities = ()
@@ -400,15 +399,15 @@ def Ne(left, right):
     return ~Eq(left, right)
 
 @_polymorphic
-def Gt(left, right):
+def Ge(left, right):
     """
-    Create the polyhedron with constraints expr1 > expr2 > expr3 ...
+    Create the polyhedron with constraints expr1 >= expr2 >= expr3 ...
     """
-    return Polyhedron([], [left - right - 1])
+    return Polyhedron([], [left - right])
 
 @_polymorphic
-def Ge(left, right):
+def Gt(left, right):
     """
-    Create the polyhedron with constraints expr1 >= expr2 >= expr3 ...
+    Create the polyhedron with constraints expr1 > expr2 > expr3 ...
     """
-    return Polyhedron([], [left - right])
+    return Polyhedron([], [left - right - 1])