OBD Reasoner
The OBD reasoner uses definitions of transitive relations, relation hierarchies, and relation compositions to infer implicit information. These inferences are added to the OBD Phenoscape database. This section documents the inherited code in Perl and embedded SQL, that extracts implicit inferences from the downloaded ontologies and annotations of ZFIN and Phenoscape phenotypes.
Contents
Notation
When describing rules below, we use the following notations:
- A, B, C: classes (as subjects or objects)
- a, b, c: individuals (as subjects or objects)
- R: relationship (predicate)
- R(A, B): A R B, for example A is_a B. This is the functional form.
Relationships Used
Transitive Relationships
Rule: <math>\forall</math>A, B, C, R and R transitive: R(A, B) <math>\and</math> R(B, C) <math>\Rightarrow</math> R(A, C)
Transitive relationships are the simplest inferences to be extracted and comprise the majority of new assertions added by the reasoner. Transitive relationships include (ontology in brackets):
- is_a (OBO Relations)
- has_part (OBO Relations)
- part_of (OBO Relations)
- integral_part_of (OBO Relations)
- has_integral_part (OBO Relations)
- proper_part_of (OBO Relations)
- has_proper_part (OBO Relations)
- improper_part_of (OBO Relations)
- has_improper_part (OBO Relations)
- location_of (OBO Relations)
- located_in (OBO Relations)
- derives_from (OBO Relations)
- derived_into (OBO Relations)
- precedes (OBO Relations)
- preceded_by (OBO Relations)
- develops_from (Zebrafish Anatomy)
- anterior_to (Spatial Ontology)
- posterior_to (Spatial Ontology)
- proximal_to (Spatial Ontology)
- distal_to (Spatial Ontology)
- dorsal_to (Spatial Ontology)
- ventral_to (Spatial Ontology)
- surrounds (Spatial Ontology)
- surrounded_by (Spatial Ontology)
- superficial_to (Spatial Ontology)
- deep_to (Spatial Ontology)
- left_of (Spatial Ontology)
- right_of (Spatial Ontology)
- complete_evidence_for_feature(Sequence Ontology)
- evidence_for_feature (Sequence Ontology)
- derives_from (Sequence Ontology)
- member_of (Sequence Ontology)
- exhibits (Phenoscape Ontology)
Relation (role) compositions
Rule: <math>\forall</math>A, B, C, R: R(A, B) <math>\and</math> is_a(B, C) <math>\Rightarrow</math> R(A, C)
Rule: <math>\forall</math>A, B, C, R: is_a(A, B) <math>\and</math> R(B, C) <math>\Rightarrow</math> R(A, C)
Relation (role) compositions are of the form A R1 B, B R2 C => A (R1|R2) C. For example, given A is_a B and B part_of C then A part_of C. The reasoner extracts such inferences and adds them to the database. Specifically, the following relation composition templates are used:
- A is_a B, B R C => A R C, where R can be any relation
- A R B, B is_a C => A R C, where R can be any relation
- Reflexive relations (A is_a A)
- Sub relations A R B, R is_a R2 => A R2 B
- An example: If A father_of B and father_of is_a parent_of, then A parent_of B
- Relation chains
- Relation chains are a special case of relation composition. Component relations are accumulated into an assembly relation. Specifically, instances of the relation inheres_in_part_of are accumulated from instances of the relations of inheres_in and part_of. IF A inheres_in B and B part_of C, THEN A inheres_in_part_of C
Intersection Relations
Phenotype annotations are typically "post-composed", where an entity and quality are combined into a Compositional Description. For example, an annotation about the quality decreased size (PATO:0000587) of the entity Dorsal Fin (TAO:0001173) may be post-composed into a Compositional Description that looks like PATO:0000587^OBO_REL:inheres_in(TAO:0001173). Instances of is_a and inheres_in relations are extracted from post compositions like this. In the above example, the reasoner extracts:
- PATO:0000587^OBO_REL:inheres_in(TAO:0001173) OBO_REL:inheres_in TAO:0001173, and
- PATO:0000587^OBO_REL:inheres_in(TAO:0001173) OBO_REL:is_a PATO:0000587
Sweeps
A reasoner functions over several sweeps. In each sweep, new implicit inferences are derived from the explicit annotations (as described in the previous sections) and added to the database. In the following sweep, inferences added from the previous sweep are used to extract further inferences. This process continues until no additional inferences are added in a sweep. This is when the deductive closure of the inference procedure is reached. No further inferences are possible and the reasoner exits.
