Implement categorical decreed variables (#474)

doc/_src_docs/applications/Mixed_Hier_usage.rstx

@@ -43,6 +43,11 @@ The design space definition uses the framework of Audet et al. [2]_ to manage bo
 hierarchical variables. We distinguish dimensional (or meta) variables which are a special type of variables that may
 affect the dimension of the problem and decide if some other decreed variables are acting or non-acting.
 
+Additionally, it is also possible to define value constraints that explicitly forbid two variables from having some
+values simultaneously. This can be useful for modeling incompatibility relationships: for example, engines can't be
+installed on the back of the fuselage (vs on the wings) if a normal tail (vs T-tail) is selected. Note: this feature
+is only available if ConfigSpace has been installed: `pip install smt[cs]`
+
 The hierarchy relationships are specified after instantiating the design space:
 
 

requirements.txt

@@ -7,4 +7,5 @@ numba        # JIT compiler
 matplotlib   # used in examples and tests
 pytest       # tests runner
 pytest-xdist # allows running parallel testing with pytest -n <num_workers>
-black        # check code format
+black        # check code format
+ConfigSpace~=0.6.1

setup.py

@@ -112,6 +112,9 @@
         "numba": [  # pip install smt[numba]
             "numba~=0.56.4",
         ],
+        "cs": [  # pip install smt[cs]
+            "ConfigSpace~=0.6.1",
+        ],
     },
     python_requires=">=3.7",
     zip_safe=False,

smt/applications/tests/test_ego.py

@@ -997,8 +997,8 @@ def f_obj(X):
             n_start=15,
         )
         x_opt, y_opt, dnk, x_data, y_data = ego.optimize(fun=f_obj)
-        self.assertAlmostEqual(np.sum(y_data), 2.03831406306514, delta=1e-4)
-        self.assertAlmostEqual(np.sum(x_data), 33.56885202767958, delta=1e-4)
+        self.assertAlmostEqual(np.sum(y_data), 2.7639515433083854, delta=1e-4)
+        self.assertAlmostEqual(np.sum(x_data), 32.11001423996299, delta=1e-4)
 
     def test_ego_gek(self):
         ego, fun = self.initialize_ego_gek()