Fig. 5From: RNA secondary structure factorization in prime tanglesExamples of tangles. a A graphical representation of a tangle in \({\mathcal {B}}_{4}\). Its invariant is \(1:2,3:2',4:3',1':4'\). b \(I_4 = 1:1', 2:2',3:3',4:4'\), the identity tangle for \({\mathcal {B}}_{4}\)Back to article page