Equality refacto (#209)

* Equality refacto

* Add and update tests

* Update reference MPS

Author: tbittar

src/gems/model/constraint.py

@@ -75,6 +75,14 @@ def __post_init__(
             if is_unbounded(self.upper_bound) and not is_non_negative(self.upper_bound):
                 raise ValueError("Upper bound should not be -Inf")
 
+    @property
+    def is_equality(self) -> bool:
+        return (
+            not is_unbounded(self.lower_bound)
+            and not is_unbounded(self.upper_bound)
+            and expressions_equal(self.lower_bound, self.upper_bound)
+        )
+
     def replicate(self, /, **changes: Any) -> "Constraint":
         return replace(self, **changes)
 

src/gems/simulation/optimization.py

@@ -691,23 +691,22 @@ def _create_constraints_for_model(
                 # Sanitize constraint name for LP format (spaces → underscores)
                 safe_name = constraint.name.replace(" ", "_").replace("-", "_")
 
-                # Lower bound constraint: lhs >= lb  (if lb != -inf)
-                if not is_unbounded(constraint.lower_bound):
+                if constraint.is_equality:
                     lb = visit(constraint.lower_bound, builder)
                     if validity_mask is not None:
                         lb = _apply_validity_mask(lb, validity_mask)
-                    name = f"{prefix}__{safe_name}__lb"
-                    con_lb = lhs >= lb  # type: ignore[operator]
-                    self.linopy_model.add_constraints(con_lb, name=name)  # type: ignore[arg-type]
-
-                # Upper bound constraint: lhs <= ub  (if ub != +inf)
-                if not is_unbounded(constraint.upper_bound):
-                    ub = visit(constraint.upper_bound, builder)
-                    if validity_mask is not None:
-                        ub = _apply_validity_mask(ub, validity_mask)
-                    name = f"{prefix}__{safe_name}__ub"
-                    con_ub = lhs <= ub  # type: ignore[operator]
-                    self.linopy_model.add_constraints(con_ub, name=name)  # type: ignore[arg-type]
+                    self.linopy_model.add_constraints(lhs == lb, name=f"{prefix}__{safe_name}__eq")  # type: ignore[operator,arg-type]
+                else:
+                    if not is_unbounded(constraint.lower_bound):
+                        lb = visit(constraint.lower_bound, builder)
+                        if validity_mask is not None:
+                            lb = _apply_validity_mask(lb, validity_mask)
+                        self.linopy_model.add_constraints(lhs >= lb, name=f"{prefix}__{safe_name}__lb")  # type: ignore[operator,arg-type]
+                    if not is_unbounded(constraint.upper_bound):
+                        ub = visit(constraint.upper_bound, builder)
+                        if validity_mask is not None:
+                            ub = _apply_validity_mask(ub, validity_mask)
+                        self.linopy_model.add_constraints(lhs <= ub, name=f"{prefix}__{safe_name}__ub")  # type: ignore[operator,arg-type]
 
     def _add_objectives_for_model(
         self,

tests/e2e/functional/studies/13_1/expected_outputs/subproblem.mps

@@ -1,30 +1,24 @@
 NAME        
 ROWS
  N  Obj     
- G  c0      
+ E  c0      
  L  c1      
  L  c2      
- L  c3      
 COLUMNS
     x0        Obj       1
     x0        c0        -1
-    x0        c1        -1
     x1        Obj       501
     x1        c0        1
-    x1        c1        1
     x2        Obj       45
     x2        c0        1
     x2        c1        1
-    x2        c2        1
-    x3        c3        -1
+    x3        c2        -1
     x4        Obj       10
     x4        c0        1
-    x4        c1        1
-    x4        c3        1
+    x4        c2        1
 RHS
     RHS_V     c0        400
-    RHS_V     c1        400
-    RHS_V     c2        200
+    RHS_V     c1        200
 BOUNDS
  UP BOUND     x0        1000000
  UP BOUND     x1        1000000

tests/e2e/functional/studies/13_2/expected_outputs/master.mps

@@ -1,16 +1,13 @@
 NAME        
 ROWS
  N  Obj     
- G  c0      
- L  c1      
+ E  c0      
 COLUMNS
     x0        Obj       490
     x1        Obj       200
     x1        c0        1
-    x1        c1        1
     MARK0000  'MARKER'                 'INTORG'
     x2        c0        -10
-    x2        c1        -10
     MARK0001  'MARKER'                 'INTEND'
 RHS
 BOUNDS

tests/e2e/functional/studies/13_2/expected_outputs/subproblem.mps

@@ -1,36 +1,29 @@
 NAME        
 ROWS
  N  Obj     
- G  c0      
+ E  c0      
  L  c1      
  L  c2      
  L  c3      
- L  c4      
 COLUMNS
     x0        Obj       1
     x0        c0        -1
-    x0        c1        -1
     x1        Obj       501
     x1        c0        1
-    x1        c1        1
     x2        Obj       45
     x2        c0        1
     x2        c1        1
-    x2        c2        1
-    x3        c3        -1
+    x3        c2        -1
     x4        Obj       10
     x4        c0        1
-    x4        c1        1
-    x4        c3        1
-    x5        c4        -1
+    x4        c2        1
+    x5        c3        -1
     x6        Obj       10
     x6        c0        1
-    x6        c1        1
-    x6        c4        1
+    x6        c3        1
 RHS
     RHS_V     c0        400
-    RHS_V     c1        400
-    RHS_V     c2        200
+    RHS_V     c1        200
 BOUNDS
  UP BOUND     x0        1000000
  UP BOUND     x1        1000000

tests/e2e/functional/test_out_of_bounds_processing.py

@@ -140,7 +140,7 @@ def test_out_of_bounds_processing(study_id: str, expected_objective: float) -> N
 # Constraints: 2 components (gen_1, gen_2) × 3 timesteps = 6 potential instances each.
 #
 # system_cyclic_with_param_in_shift — no drop mode, all instances present:
-#   is_on_dynamics (lb + ub): 6 each
+#   is_on_dynamics (eq): 6
 #   min_up_duration (ub only): 6
 #   min_down_duration (ub only): 6
 #
@@ -151,14 +151,12 @@ def test_out_of_bounds_processing(study_id: str, expected_objective: float) -> N
 #   min_down_duration: both have d_min_down=1 → range [0,0] → never dropped → 6
 _EXPECTED_CONSTRAINT_COUNTS: Dict[str, Dict[str, int]] = {
     "system_cyclic_with_param_in_shift": {
-        f"{_GEN_PREFIX}__is_on_dynamics__lb": 6,
-        f"{_GEN_PREFIX}__is_on_dynamics__ub": 6,
+        f"{_GEN_PREFIX}__is_on_dynamics__eq": 6,
         f"{_GEN_PREFIX}__min_up_duration__ub": 6,
         f"{_GEN_PREFIX}__min_down_duration__ub": 6,
     },
     "system_drop_with_param_in_shift": {
-        f"{_GEN_PREFIX}__is_on_dynamics__lb": 4,
-        f"{_GEN_PREFIX}__is_on_dynamics__ub": 4,
+        f"{_GEN_PREFIX}__is_on_dynamics__eq": 4,
         f"{_GEN_PREFIX}__min_up_duration__ub": 5,
         f"{_GEN_PREFIX}__min_down_duration__ub": 6,
     },

tests/unittests/system/test_model.py

@@ -219,6 +219,41 @@ def test_constraint_equals() -> None:
     )
 
 
+def test_is_equality_true_for_equality_comparison() -> None:
+    c = Constraint(name="c", expression=var("x") == param("p"))
+    assert c.is_equality is True
+
+
+def test_is_equality_false_for_inequality_comparison() -> None:
+    assert Constraint(name="c", expression=var("x") <= param("p")).is_equality is False
+    assert Constraint(name="c", expression=var("x") >= param("p")).is_equality is False
+
+
+def test_is_equality_false_for_range_constraint() -> None:
+    c = Constraint(
+        name="c", expression=var("x"), lower_bound=literal(0), upper_bound=literal(10)
+    )
+    assert c.is_equality is False
+
+
+def test_is_equality_true_for_equal_explicit_bounds() -> None:
+    c = Constraint(
+        name="c", expression=var("x"), lower_bound=param("p"), upper_bound=param("p")
+    )
+    assert c.is_equality is True
+
+
+def test_is_equality_false_for_one_sided_constraint() -> None:
+    assert (
+        Constraint(name="c", expression=var("x"), lower_bound=literal(0)).is_equality
+        is False
+    )
+    assert (
+        Constraint(name="c", expression=var("x"), upper_bound=literal(0)).is_equality
+        is False
+    )
+
+
 # --- Issue #76: tolerate absence of expec() in objective contributions ---