bioinformatics - Reverse complement of reconstruction model for assembling reads -

one way assemble fragments produced dna sequencing (often called reads) seek shortest common superstring contains reads of given set of reads. 1 model problem reconstruction model, calculates minimal edit distance between possible superstring (that contains fragments) , each 1 of fragments. don't understand yet fact when calculating edit distance given fragment, it's necessary calculate edit distance reverse complement of fragment.
example of fragment , reverse complement be:

actgtcc fragment
tgacagg complement (the complementary strand know)
ggacagt reverse complement

according book i'm reading ideia behind find superstring short possible either given fragment or reverse complement must approximate substring of superstring. know many mathematical/computational models don't have biological sense way of soluting biological problem, recontruction model think it's biologically reasonable find string contains fragments of region of dna sequence, , complement fragments, after when assembling can find both strand sequence. reverse complement not exist given sequence, unless has suffered kind of break-recombination event, not expected, when talking conserved regions. idea why model takes account reverse complements ? in advance.