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Correct calculation of Constraint.equality for RangedExpression with constant bounds #2097

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Correct calculation of Constraint.equality for RangedExpression with constant bounds #2097

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11 changes: 8 additions & 3 deletions pyomo/core/base/constraint.py
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
from pyomo.core.expr import logical_expr
from pyomo.core.expr.numvalue import (
NumericValue, value, as_numeric, is_fixed, native_numeric_types,
is_constant,
)
from pyomo.core.base.component import (
ActiveComponentData, ModelComponentFactory,
Expand Down Expand Up @@ -411,9 +412,13 @@ def equality(self):
if self._expr.__class__ is logical_expr.EqualityExpression:
return True
elif self._expr.__class__ is logical_expr.RangedExpression:
# TODO: this is a very restrictive form of structural equality.
lb = self._expr.arg(0)
if lb is not None and lb is self._expr.arg(2):
lb, _, ub = self._expr.args
if lb is None:
return False # unbounded
if lb is ub:
return True # structurally equal
if is_constant(lb) and is_constant(ub) and value(lb) == value(ub):
# Should we consider an equality tolerance?
return True
return False

Expand Down
103 changes: 99 additions & 4 deletions pyomo/core/tests/unit/test_con.py
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Original file line number Diff line number Diff line change
Expand Up @@ -170,10 +170,105 @@ def rule(model):
return (0, model.y, 1)
model.c = Constraint(rule=rule)

self.assertEqual(model.c.equality, False)
self.assertEqual(model.c.lower, 0)
self.assertIs (model.c.body, model.y)
self.assertEqual(model.c.upper, 1)
self.assertEqual(model.c.equality, False)
self.assertEqual(model.c.lower, 0)
self.assertIs (model.c.body, model.y)
self.assertEqual(model.c.upper, 1)

model = self.create_model()
def rule(model):
return (0, model.y, 0)
model.c = Constraint(rule=rule)

self.assertEqual(model.c.equality, True)
self.assertEqual(model.c.lower, 0)
self.assertIs (model.c.body, model.y)
self.assertEqual(model.c.upper, 0)

# Test mixed bound types (int / float)
model = self.create_model()
def rule(model):
return (0, model.y, 0.)
model.c = Constraint(rule=rule)

self.assertEqual(model.c.equality, True)
self.assertEqual(model.c.lower, 0)
self.assertIs (model.c.body, model.y)
self.assertEqual(model.c.upper, 0)

def test_tuple_construct_2sided_mutable_inequality(self):
model = self.create_model()
model.p = Param(initialize=0, mutable=True)
model.q = Param(initialize=0., mutable=True)
def rule(model):
return (0, model.y, model.q)
model.c = Constraint(rule=rule)

self.assertEqual(model.c.equality, False)
self.assertEqual(model.c.lower, 0)
self.assertIs(model.c.body, model.y)
self.assertIs(model.c.upper, model.q)
self.assertEqual(model.c.lb, 0)
self.assertEqual(model.c.ub, 0)

def rule(model):
return (model.p, model.y, 0)
model.d = Constraint(rule=rule)

self.assertEqual(model.d.equality, False)
self.assertIs(model.d.lower, model.p)
self.assertIs(model.d.body, model.y)
self.assertEqual(model.d.upper, 0)
self.assertEqual(model.d.lb, 0)
self.assertEqual(model.d.ub, 0)

def rule(model):
return (model.p, model.y, model.q)
model.e = Constraint(rule=rule)

self.assertEqual(model.e.equality, False)
self.assertIs(model.e.lower, model.p)
self.assertIs(model.e.body, model.y)
self.assertIs(model.e.upper, model.q)
self.assertEqual(model.e.lb, 0)
self.assertEqual(model.e.ub, 0)

def test_tuple_construct_2sided_immutable_inequality(self):
model = self.create_model()
model.p = Param(initialize=0, mutable=False)
model.q = Param(initialize=0., mutable=False)
def rule(model):
return (0, model.y, model.q)
model.c = Constraint(rule=rule)

self.assertEqual(model.c.equality, True)
self.assertEqual(model.c.lower, 0)
self.assertIs(model.c.body, model.y)
self.assertIs(model.c.upper, model.q)
self.assertEqual(model.c.lb, 0)
self.assertEqual(model.c.ub, 0)

def rule(model):
return (model.p, model.y, 0)
model.d = Constraint(rule=rule)

self.assertEqual(model.d.equality, True)
self.assertIs(model.d.lower, model.p)
self.assertIs(model.d.body, model.y)
self.assertEqual(model.d.upper, 0)
self.assertEqual(model.d.lb, 0)
self.assertEqual(model.d.ub, 0)

def rule(model):
return (model.p, model.y, model.q)
model.e = Constraint(rule=rule)

self.assertEqual(model.e.equality, True)
self.assertIs(model.e.lower, model.p)
self.assertIs(model.e.body, model.y)
self.assertIs(model.e.upper, model.q)
self.assertEqual(model.e.lb, 0)
self.assertEqual(model.e.ub, 0)

def test_tuple_construct_invalid_2sided_inequality(self):
model = self.create_model(abstract=True)
Expand Down