Reciprocal best hit and reciprocal best alignment heuristic

Reciprocal best hit (RBH) and reciprocal best alignment heuristic (RBAH) is similar to each other.

However, RBH can not detect  A - B and A' - B' pair (or A - B' and A' - B pair) in the following case.

A is best similar to B and A' is best similar to B'.

B is best similar to A' and B' is best similar to A.

RBAH considers this problem of RBH and as k-best blast hit is used, RBAH can detect either A - B and A' - B' pair or A - B' and A' - B pair.

* k-best blast hit: the list of blast hit from top to k_th best.

*Reference

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