Fix compilation error

gtsam/hybrid/HybridFactor.h

@@ -36,8 +36,6 @@ typedef HybridFactor This; ///< This class
   typedef boost::shared_ptr<HybridFactor> shared_ptr; ///< shared_ptr to this class
   typedef Factor Base; ///< Our base class
 
-using Values = Values; ///< backwards compatibility
-
 public:
 
 /// @name Standard Constructors
@@ -78,6 +76,7 @@ Base::print(s, formatter);
 // HybridFactor
 
 // traits
-template<> struct traits<HybridFactor> : public Testable<HybridFactor> {};
+template<>
+struct traits<HybridFactor> : public Testable<HybridFactor> {};
 
 }// namespace gtsam

gtsam/hybrid/HybridFactorGraph.cpp

@@ -29,6 +29,9 @@ EliminateHybrid(const HybridFactorGraph &factors,
   // The issue here is that, how can we know which variable is discrete if we
   // unify Values? Obviously we can tell using the factors, but is that fast?
 
+  // In the case of multifrontal, we will need to use a constrained ordering
+  // so that the discrete parts will be guaranteed to be eliminated last!
+
   // PRODUCT: multiply all factors
   gttic(product);
   KeySet allKeys;