diff --git a/gtsam_unstable/partition/FindSeparator-inl.h b/gtsam_unstable/partition/FindSeparator-inl.h
index 0e4950b79..45868e78e 100644
--- a/gtsam_unstable/partition/FindSeparator-inl.h
+++ b/gtsam_unstable/partition/FindSeparator-inl.h
@@ -13,6 +13,7 @@
 #include <stdexcept>
 #include <iostream>
 #include <vector>
+#include <optional>
 #include <boost/tuple/tuple.hpp>
 #include <boost/shared_array.hpp>
 
@@ -237,7 +238,7 @@ namespace gtsam { namespace partition {
 
   /* ************************************************************************* */
   template<class GenericGraph>
-  boost::optional<MetisResult> separatorPartitionByMetis(const GenericGraph& graph,
+  std::optional<MetisResult> separatorPartitionByMetis(const GenericGraph& graph,
     const std::vector<size_t>& keys, WorkSpace& workspace, bool verbose) {
     // create a metis graph
     size_t numKeys = keys.size();
@@ -252,7 +253,7 @@ namespace gtsam { namespace partition {
     size_t sepsize;
     sharedInts part;
     boost::tie(sepsize, part) = separatorMetis(numKeys, xadj, adjncy, adjwgt, verbose);
-    if (!sepsize)  return boost::optional<MetisResult>();
+    if (!sepsize)  return std::optional<MetisResult>();
 
     // convert the 0-1-2 from Metis to 1-2-0, so that the separator is 0, as later
     //  we will have more submaps
@@ -291,7 +292,7 @@ namespace gtsam { namespace partition {
 
   /* *************************************************************************/
   template<class GenericGraph>
-  boost::optional<MetisResult> edgePartitionByMetis(const GenericGraph& graph,
+  std::optional<MetisResult> edgePartitionByMetis(const GenericGraph& graph,
    const std::vector<size_t>& keys, WorkSpace& workspace, bool verbose) {
 
     // a small hack for handling the camera1-camera2 case used in the unit tests
@@ -443,15 +444,15 @@ namespace gtsam { namespace partition {
 
   /* ************************************************************************* */
   template<class GenericGraph>
-  boost::optional<MetisResult> findPartitoning(const GenericGraph& graph, const std::vector<size_t>& keys,
+  std::optional<MetisResult> findPartitoning(const GenericGraph& graph, const std::vector<size_t>& keys,
       WorkSpace& workspace, bool verbose,
-      const boost::optional<std::vector<Symbol> >& int2symbol, const bool reduceGraph) {
-    boost::optional<MetisResult> result;
+      const std::optional<std::vector<Symbol> >& int2symbol, const bool reduceGraph) {
+    std::optional<MetisResult> result;
     GenericGraph reducedGraph;
     std::vector<size_t> keyToPartition;
     std::vector<size_t> cameraKeys, landmarkKeys;
     if (reduceGraph) {
-      if (!int2symbol.is_initialized())
+      if (!int2symbol.has_value())
         throw std::invalid_argument("findSeparator: int2symbol must be valid!");
 
       // find out all the landmark keys, which are to be eliminated
@@ -474,9 +475,9 @@ namespace gtsam { namespace partition {
     }  else // call Metis to partition the graph to A, B, C
       result = separatorPartitionByMetis(graph, keys, workspace, verbose);
 
-    if (!result.is_initialized()) {
+    if (!result.has_value()) {
       std::cout << "metis failed!" << std::endl;
-      return boost::none;
+      return {};
     }
 
     if (reduceGraph) {
@@ -491,10 +492,10 @@ namespace gtsam { namespace partition {
   template<class GenericGraph>
   int findSeparator(const GenericGraph& graph, const std::vector<size_t>& keys,
       const int minNodesPerMap, WorkSpace& workspace, bool verbose,
-      const boost::optional<std::vector<Symbol> >& int2symbol, const bool reduceGraph,
+      const std::optional<std::vector<Symbol> >& int2symbol, const bool reduceGraph,
       const int minNrConstraintsPerCamera, const int minNrConstraintsPerLandmark) {
 
-    boost::optional<MetisResult> result = findPartitoning(graph, keys, workspace,
+    std::optional<MetisResult> result = findPartitoning(graph, keys, workspace,
       verbose, int2symbol, reduceGraph);
 
     // find the island in A and B, and make them separated submaps
diff --git a/gtsam_unstable/partition/FindSeparator.h b/gtsam_unstable/partition/FindSeparator.h
index f4342695b..9a6c61800 100644
--- a/gtsam_unstable/partition/FindSeparator.h
+++ b/gtsam_unstable/partition/FindSeparator.h
@@ -31,7 +31,7 @@ namespace gtsam { namespace partition {
    * the size of dictionary mush be equal to the number of variables in the original graph (the largest one)
    */
   template<class GenericGraph>
-  boost::optional<MetisResult> separatorPartitionByMetis(const GenericGraph& graph, const std::vector<size_t>& keys,
+  std::optional<MetisResult> separatorPartitionByMetis(const GenericGraph& graph, const std::vector<size_t>& keys,
       WorkSpace& workspace, bool verbose);
 
   /**
@@ -40,7 +40,7 @@ namespace gtsam { namespace partition {
    */
   template<class GenericGraph>
   int findSeparator(const GenericGraph& graph, const std::vector<size_t>& keys,
-      const int minNodesPerMap, WorkSpace& workspace, bool verbose, const boost::optional<std::vector<Symbol> >& int2symbol,
+      const int minNodesPerMap, WorkSpace& workspace, bool verbose, const std::optional<std::vector<Symbol> >& int2symbol,
       const bool reduceGraph, const int minNrConstraintsPerCamera, const int minNrConstraintsPerLandmark);
 
 }} //namespace
diff --git a/gtsam_unstable/partition/tests/testFindSeparator.cpp b/gtsam_unstable/partition/tests/testFindSeparator.cpp
index 49796f80d..b086be7ff 100644
--- a/gtsam_unstable/partition/tests/testFindSeparator.cpp
+++ b/gtsam_unstable/partition/tests/testFindSeparator.cpp
@@ -29,10 +29,10 @@ TEST ( Partition, separatorPartitionByMetis )
   std::vector<size_t> keys{0, 1, 2, 3, 4};
 
   WorkSpace workspace(5);
-  boost::optional<MetisResult> actual = separatorPartitionByMetis<GenericGraph2D>(graph, keys,
+  std::optional<MetisResult> actual = separatorPartitionByMetis<GenericGraph2D>(graph, keys,
    workspace, true);
 
-  CHECK(actual.is_initialized());
+  CHECK(actual.has_value());
   vector<size_t> A_expected{0, 3}; // frontal
   vector<size_t> B_expected{2, 4}; // frontal
   vector<size_t> C_expected{1};    // separator
@@ -54,10 +54,10 @@ TEST ( Partition, separatorPartitionByMetis2 )
   std::vector<size_t> keys{1, 2, 3, 5, 6};
 
   WorkSpace workspace(8);
-  boost::optional<MetisResult> actual = separatorPartitionByMetis<GenericGraph2D>(graph, keys,
+  std::optional<MetisResult> actual = separatorPartitionByMetis<GenericGraph2D>(graph, keys,
    workspace, true);
 
-  CHECK(actual.is_initialized());
+  CHECK(actual.has_value());
   vector<size_t> A_expected{1, 5}; // frontal
   vector<size_t> B_expected{3, 6}; // frontal
   vector<size_t> C_expected{2};    // separator
@@ -77,10 +77,10 @@ TEST ( Partition, edgePartitionByMetis )
   std::vector<size_t> keys{0, 1, 2, 3};
 
   WorkSpace workspace(6);
-  boost::optional<MetisResult> actual = edgePartitionByMetis<GenericGraph3D>(graph, keys,
+  std::optional<MetisResult> actual = edgePartitionByMetis<GenericGraph3D>(graph, keys,
    workspace, true);
 
-  CHECK(actual.is_initialized());
+  CHECK(actual.has_value());
   vector<size_t> A_expected{0, 1}; // frontal
   vector<size_t> B_expected{2, 3}; // frontal
   vector<size_t> C_expected;    // separator
@@ -108,9 +108,9 @@ TEST ( Partition, edgePartitionByMetis2 )
   std::vector<size_t> keys{0, 1, 2, 3, 4};
 
   WorkSpace workspace(6);
-  boost::optional<MetisResult> actual = edgePartitionByMetis<GenericGraph3D>(graph, keys,
+  std::optional<MetisResult> actual = edgePartitionByMetis<GenericGraph3D>(graph, keys,
    workspace, true);
-  CHECK(actual.is_initialized());
+  CHECK(actual.has_value());
   vector<size_t> A_expected{0, 1}; // frontal
   vector<size_t> B_expected{2, 3, 4}; // frontal
   vector<size_t> C_expected;    // separator
@@ -135,7 +135,7 @@ TEST ( Partition, findSeparator )
   int minNodesPerMap = -1;
   bool reduceGraph = false;
   int numSubmaps = findSeparator<GenericGraph2D>(graph, keys, minNodesPerMap, workspace,
-    false, boost::none, reduceGraph, 0, 0);
+    false, {}, reduceGraph, 0, 0);
   LONGS_EQUAL(2, numSubmaps);
   LONGS_EQUAL(5, workspace.partitionTable.size());
   LONGS_EQUAL(1, workspace.partitionTable[0]);
@@ -161,7 +161,7 @@ TEST ( Partition, findSeparator2 )
   int minNodesPerMap = -1;
   bool reduceGraph = false;
   int numSubmaps = findSeparator<GenericGraph2D>(graph, keys, minNodesPerMap, workspace,
-    false, boost::none, reduceGraph, 0, 0);
+    false, {}, reduceGraph, 0, 0);
   LONGS_EQUAL(2, numSubmaps);
   LONGS_EQUAL(8, workspace.partitionTable.size());
   LONGS_EQUAL(-1,workspace.partitionTable[0]);