1 files changed, 19 insertions, 0 deletions

diff --git a/src/pruning.c b/src/pruning.c
index b000eb7..5073d69 100644
--- a/src/pruning.c
+++ b/src/pruning.c
@@ -167,6 +167,25 @@ genptable_branch(PruneData *pd, uint64_t ind, int d, Move *ms)
          * This is a terribly inefficient way to deal with this.
          * TODO: make it more efficient.
          */
+        /*
+         * IDEA (with the example of khuge in mind):
+         * The problem only happens when two position that are actually
+         * in the same class are considered different. This can happen
+         * because only CO is used to determine which transformation
+         * to apply to get a representative for the class. So if the
+         * corners are in a self-symmetric position more than one
+         * transformation to the representative is possible, only one
+         * (essentially at random) is picked, but this is not necessarily
+         * the correct one if the edges are not in a self-symmetric
+         * position.
+         * SOLUTION: Keep in mind which corner positions are
+         * self-symmetric (add a field to symdata). Add a function
+         * to coord that tells if a position has this problem, or
+         * even the list of transformations that need to be tried.
+         * The second option is a bit more complicated but more
+         * efficient and allows for removing the ntrans and trans
+         * field from struct coordinate.
+         */
         for (i = 0; i < pd->coord->ntrans; i++) {
                 c = i == 0 ? ci :
                              apply_trans(pd->coord->trans[i], ci);