Pathfinding - A* with least turns

Question

Is it possible to modify A* to return the shortest path with the least number of turns?

One complication: Nodes can no longer be distinguished solel

Answer 1

Is it possible to modify A* to return the shortest path with the least number of turns?

It is most likely not possible. The reason being that it is an example of the weight-constrained shortest path problem. It is therefore NP-Complete and cannot be solved efficiently.

You can find papers that discuss solving this problem e.g. http://web.stanford.edu/~shushman/math15_report.pdf