kmer key

The Kmer-key of a kmer is the lexically lowest value of a kmer and its reverse complement. For odd values of k, no kmer can match its reverse complement. McCortex stores kmer-keys (rather than kmers) in the hash table.

e.g. kmer-key: AACGG, reverse complement of kmer-key: TTGCC

Since we don't know if we are sequencing the forward or reverse strand, mapping kmers to their kmer-keys means a given kmer sequenced on either strand is mapped to the same kmer-key in the de Bruijn graph (aka a big hash table of kmers).