Hi all, I'm observing a weird phenomenon when iterating over a binomial heap after pushing two values with the same priority. Instead of printing the expected values twice, the ordered iterator seems to print three values. I do not observe this behavior when using a Fibonacci heap or a binary heap. I've attached sample code that demonstrates this behavior. Can anyone help explain what's going on? Boost Version : Boost 1.64 Compiler : GCC 5.3.0 #include <iostream> #include "boost/heap/fibonacci_heap.hpp" #include "boost/heap/binomial_heap.hpp" #include "boost/heap/d_ary_heap.hpp" template <class HeapType> void PrintHeap(HeapType const & heap) { std::cout << "Printing out heap : "; for (auto it = heap.begin(); it != heap.end(); ++it) { std::cout << *it << " "; } std::cout << "\n Printing out heap in order : "; for (auto it = heap.ordered_begin(); it != heap.ordered_end(); ++it) { std::cout << *it << " "; } std::cout << "\n\n"; } int main(int /* argc */, char** /* argv */) { typedef boost::heap::binomial_heap<int> BinomialHeap; BinomialHeap binomial_heap; binomial_heap.push(1); binomial_heap.push(1); // Prints {1,1} and {1,1,1} PrintHeap(binomial_heap); typedef boost::heap::fibonacci_heap<int> FibonacciHeap; FibonacciHeap fibonacci_heap; fibonacci_heap.push(1); fibonacci_heap.push(1); // Prints {1,1} and {1,1} PrintHeap(fibonacci_heap); typedef boost::heap::d_ary_heap, boost::heap::mutable_<true>> BinaryHeap; BinaryHeap binary_heap; binary_heap.push(1); binary_heap.push(1); // Prints {1,1} and {1,1} PrintHeap(binary_heap); } Thanks! Jun