An ontology-based search engine for protein-protein interactions

BMC Bioinformatics

Table 2 Modified Gödel number representation.

Term	Prime number	Relation	Modified Gödel Number
Term1	2
Term2	3	R1: Term2 is a Term1	relation(is a) = 3 × 2 = 6
Term3	5	R2: Term3 is part of Term2	relation(part of) = 5 × 3 × 2 = 30
Term4	7	R3: Term4 is a Term2	relation(is a) = 7 × 3 × 2 = 42

Each term is assigned a prime number instead of natural number, and each relation is denoted by a modified Gödel number, which is a multiplication of prime numbers representing the term and its ancestors in the ontology hierarchy. For example, relation R3 is denoted by 42, which has prime factors 2 (Term1, root node in the hierarchy), 3 (Term2), and 7 (Term3). Using this representation, relation R3 can be easily inferred by unique factorization of it into primes (Term1, Term2, and Term3).

ISSN: 1471-2105