Figure 2
From: Efficient pairwise RNA structure prediction using probabilistic alignment constraints in Dynalign
Illustration of alignment of nucleotide at n1 in 1st sequence and nucleotide at n2 in 2nd sequence and how forward and backward variables are related to alignment of n1 and n2. Forward variable keeps track of events before alignment position (n1, n2) and backward variable keeps track of events after alignment position (n1, n2).
