Unraveling unbreakable hairpins: characterizing RNA secondary structures that are persistent after dinucleotide shuffling

(A) An example of a secondary structure of an unbreakable hairpin. (B) The de Bruijn graph representation of the unbreakable hairpin in A. Graph edges correspond to dinucleotides in the sequence, whereas the red edge indicates a false edge from the last nucleotide to the first. (C) An example of a secondary structure of a breakable hairpin. (D) The de Bruijn graph representation of the breakable hairpin in C, with edges defined as in B.