I am trying to keep a heap sorted by values in a property map. I tried the code below, but the compiler does not like my arguments to the heap constructor (PriorityQueueType pq(indirectComparison);). According to the documentation (http://www.boost.org/doc/libs/1_51_0/doc/html/boost/heap/binomial_heap.html), there is a constructor: explicit binomial_heap(value_compare const & = value_compare()); that takes a value_compare, which I was thinking would of type IndirectComparisonType that I provided (I don't really understand the optional template arguments and the base_maker::compare_argument type of things)? Here is the indirect_cmp doc for reference: http://www.boost.org/doc/libs/1_51_0/boost/pending/indirect_cmp.hpp #include <boost/heap/binomial_heap.hpp> #include <boost/pending/indirect_cmp.hpp> #include <boost/array.hpp> #include <boost/graph/grid_graph.hpp> #include <iostream> int main(int, char*[]) { // Construct a graph boost::array<std::size_t, 2> lengths = { { 2,2 } }; typedef boost::grid_graph<2> GraphType; GraphType graph(lengths); typedef boost::graph_traits<GraphType>::vertex_descriptor Vertex; typedef boost::property_map<GraphType, boost::vertex_index_t>::const_type GridIndexMapType; GridIndexMapType gridIndexMap(get(boost::vertex_index, graph)); // Construct a property map typedef boost::vector_property_map<float, GridIndexMapType> PriorityMapType; PriorityMapType priorityMap(gridIndexMap); // Construct the indirect comparison functor typedef boost::indirect_cmp<PriorityMapType, std::less<float> > IndirectComparisonType; IndirectComparisonType indirectComparison(priorityMap); // Construct the queue typedef int ValueType; typedef boost::heap::binomial_heap<ValueType, boost::heap::stable<false>, IndirectComparisonType> PriorityQueueType; PriorityQueueType pq(indirectComparison); return 0; } Does anyone know how to provide this indirect comparison functor to the queue properly? Thanks, David