Fig. 2

Inside and outside variables. \(c_k\) denotes the concestor nodes on the target lineage. \(b_k\) denotes the sibling node of \(c_{k-1}\). \(\alpha (b_k,*)\) represents the inside variable, while \(\beta (c_k,*)\) represents the outside variable. \(\gamma (b_k,*)\) represents a dynamic programming variable in Eq. 2 in the main text