Added notes on possible performance improvements for H48

1 files changed, 20 insertions, 0 deletions

diff --git a/doc/h48.md b/doc/h48.md
index 30b5171..3781863 100644
--- a/doc/h48.md
+++ b/doc/h48.md
@@ -432,3 +432,23 @@ Moreover, in this case one can optimize it further by avoiding to repeat
 the search from a coordinate that has already been visited. (Work
 in progress - this method will be replaced in the future by a more
 efficient one)
+
+## Possible future improvements
+
+*This section should be considered more of a draft with personal
+notes, unlike the rest of the document.*
+
+There are some areas where this implementation of the H48 optimal solver
+can be improved:
+
+* Interwtining fallback tables to the main table. This is a trick that
+  nxopt uses to reduce the number of cache misses, but we have not
+  implemented in H48 yet.
+* Faster pruning table generation for **h11** and **h0**. Since these
+  two coordinates are "real" coordinates, we can use a different technique
+  to generate their tables faster. This won't affect the solver speed.
+* Use
+  [BPMX](https://webdocs.cs.ualberta.ca/~nathanst/papers/AStar_Inconsistent.pdf)
+  to improve pruning estimation. This optimization sped up
+  [vcube](https://github.com/Voltara/vcube/commit/a5b08f51793f81ac34c1d402f2627f6a0495c636).
+  by about 5%-10%. Suggested by Arhan Chaudhary pointed out.