Compression
(1) Raw Compression (Hbonds):
Craw = (?i ? 1..n N(Hi)) - (n-1)*N(Hp)
sum of hbonds in the examples minus (No_of_examples - 1) * hbonds in pattern
(2) Normalised compression:
Cnorm = 1 - ((?i ? 1..n N(Hi))- Craw) / ((?i ? 1..n N(Hi))- min(N(Hi)))
This is a goodness of compression measure (0=good, 1=bad).