efficient mapping of short reads with periodic spaced seeds

 PerM is a software package which was designed to perform highly efficient
 genome scale alignments for hundreds of millions of short reads produced by
 the ABI SOLiD and Illumina sequencing platforms. Today PerM is capable of
 providing full sensitivity for alignments within 4 mismatches for 50bp SOLID
 reads and 9 mismatches for 100bp Illumina reads.