A* Algorithm with know Costs

Question

I'm working on the A* Algorithm. I have these questions:

1. Is it possible to use different heuristics in the same search process? For some nodes I have the actual cost from each of these nodes to the end node. Can I use this cost as the heuristic for these nodes, while for the other nodes (for which I don't know the cost to end node) I calculate the heuristics using Euclidean or other metrics? I tried this, but the algorithm couldn't find the End Node!!!
2. I have a part of search space that is searched using A*. The search space has been increased (by which I mean the boundaries around the original search space). How can I use information from original search process to make the new search process in the increased space search more informed? (if there are papers related to these topics, please inform me!)

Thanks a lot for any information.

Answer 1

1) As long as your heuristics are admissible, the algorithm should find the answer. An admissible heuristic is a heuristic that never overestimates the distance to the goal.

2) You could use the values you already know as part of your heuristic for the expanded space.