1 Motif extraction problem 

Motif extraction is one of the important problems in genetic information 
processing. It extracts common patterns(motifs) from amino acid sequences 
of the same protein category, which are conserved in the evolution process 
and characterize the function/structure of proteins. 

P.94 Figure 1
2 Motif evaluation by the MDL principle As a criterion for motif evaluation, the minimum description length(MDL) principle was adopted. The MDL principle selects a motif with the shortest description length defined below. Description length = Complexity of motif + Classification error rate The MDL principle enables us to compare a simple motif with exceptions and a complex motif without exceptions as illustrated below.
P.94 Figure 2
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