Do not include constant branches in minimization arguments

pytensor/tensor/optimize.py

@@ -20,6 +20,7 @@ from pytensor.graph.op import (
 from pytensor.graph.replace import graph_replace
 from pytensor.graph.traversal import (
     ancestors,
+    graph_inputs,
     truncated_graph_inputs,
 )
 from pytensor.scalar import ScalarType, ScalarVariable
@@ -147,10 +148,18 @@ def _find_optimization_parameters(
 
     This is used to determine the additional arguments that need to be passed to the objective function.
     """
+
+    def _depends_only_on_constants(var: Variable) -> bool:
+        if isinstance(var, Constant):
+            return True
+        if var.owner is None:
+            return False
+        return all(isinstance(v, Constant) for v in graph_inputs([var]))
+
     return [
         arg
         for arg in truncated_graph_inputs([objective], [x])
-        if (arg is not x and not isinstance(arg, Constant))
+        if (arg is not x and not _depends_only_on_constants(arg))
     ]
 
 

tests/tensor/test_optimize.py

@@ -17,6 +17,19 @@ from tests import unittest_tools as utt
 floatX = config.floatX
 
 
+def test_constant_expressions_not_in_args():
+    x = pt.scalar("x")
+    a = pt.scalar("a")
+
+    # cast(0, int64) is not a Constant, but depends only on constants
+    constant_expr = pt.cast(pt.constant(0), "int64")
+    out = (x - a) ** 2 + constant_expr
+
+    minimized_x, _ = minimize(out, x)
+    minimize_op_node = minimized_x.owner
+    assert minimize_op_node.inputs == [x, a]
+
+
 def test_minimize_scalar():
     x = pt.scalar("x")
     a = pt.scalar("a")