Termination Criteria for Bidirectional Search

Question

According to most of the reading I have done, a bidirectional search algorithm is said to terminate when the \"forward\" and \"backward\" frontiers first intersect. However,

Answer 1

a simple triangle would satisfy your condition, with the sides being 6,6,10 with the optimal path going through the segment of length 10. In Bi-directional, the algorithm searches the shorter path forward, then reverse would also take the shorter path, they would meet, a complete path is found

but clearly 2 segments of 6 + 6 is worse than one segment of length 10.