The rigid hybrid number for two phylogenetic trees

Recently there has been considerable interest in the problem of finding a phylogenetic network with minimum number reticulation vertices which displays given set trees, that is, hybrid number. Even so, for certain evolutionary scenarios insisting trees can be an overly restrictive assumption. In this paper, we consider less notion displaying called weakly and, particular, special case call rigidly displaying. We characterize when two displayed by temporal tree-child terms fork-picking sequences, concept is closely related to cherry-picking sequences. also show that, it exists, rigid weight sequence and quite different from beaded- temporal-hybrid numbers.