Table 8 The HI rules learnt to identify 1CPC (C-Phycocyanin) are illustrated first in their original Prolog form and in English translation. Two sets of rules are shown those using HI^all, and those learnt from HI^seq. All numbers were discretised into 10 levels for ease of symbolic induction (1 low – 10 high).

HI ^all

Prolog

homologous(A) :-

desc(A,chain),

amino_acid_ratio_rule(A,h,1).

homologous(A) :-

keyword(A,phycobilisome).

English

A protein is homologous if

a1

   it has the word 'chain' in its SWISS-PROT description line and

   it has a level 1 histidine content in the residue chain and

a2

   or it has the word 'phycobilisome' as a SWISS-PROT keyword.

HI ^seq

Prolog

homologous(A) :-

amino_acid_ratio_rule(A,w,1),

amino_acid_ratio_rule(A,h,1),

amino_acid_pair_ratio_rule(A,l,r,10).

homologous(A):-

mol_wt_rule(A,3),

sec_struc_distribution_rule(A,a,10).

English

A protein is homologous if

s1

   it has a level 1 tryptophan content and

   it has a level 1 histidine content and

   it has a level 10 leucine-arginine pair content.

s2

or

   it has a level 3 molecular weight and

   it has a level 10 predicted α-helix content.