For continuants: C is_a C' if and only if: given any c that instantiates C at a time t, c instantiates C' at t. For processes: P is_a P' if and only if: that given any p that instantiates P, then p instantiates P'. source: PMID:15892874

The is_a relationship is considered axiomatic by the obo file format specification. In the representation of obo in OWL, where obo terms are represented as OWL classes, is_a is mapped on to the subClassOf axiom

Examples

• astrocyte is_a
• glial cell
[CL]
• catabolic process is_a
• metabolic process
[GO]
• serotonin is_a
• biogenic amine
[CHEBI]

Other relations

This relation has no inverse relations declared

id	OBO_REL_C:0000001
name	is_a
properties	anti_symmetric reflexive transitive
aliases	is_a_kind_of [exact] is_subtype_of [exact] kind_of [exact] subtype_of [exact] type_of [exact]
anti_symmetric	true
holds_between
reflexive	true
symmetric
transitive	true
all_some_in_reference_context
exact_synonym	is_a_kind_of
exact_synonym	is_subtype_of
exact_synonym	kind_of
exact_synonym	subtype_of
exact_synonym	type_of
example	astrocyte is_a glial cell [CL] catabolic process is_a metabolic process [GO] serotonin is_a biogenic amine [CHEBI]
text_definition	For continuants: C is_a C' if and only if: given any c that instantiates C at a time t, c instantiates C' at t. For processes: P is_a P' if and only if: that given any p that instantiates P, then p instantiates P'.
text_definition_xref	PMID:15892874

Axioms for this relation:

axiom	is_a( X, Y) → instance_of( i, X) → instance_of( i, Y)
axiom	is_a( X, Y) → instance_of( i, X, t) → instance_of( i, Y, t)

Axioms that refer to this relation:

axiom	Axiom: occurrents (processes, stages, etc) atemporally instantiate types instance_of( x, U) → is_a( U, occurrent)
axiom	Axiom: ; http://www.acsu.buffalo.edu/~bittner3/Theories/BFO/Instantiation.html; lemma Inst_IsA_rule: [instantiation]; process instantiation: binary instance_of( i, X) ∧ is_a( X, Y) → instance_of( i, Y)
axiom	instance_of( i, X, t) ∧ is_a( X, Y) → instance_of( i, Y, t)
axiom	Axiom: continuants temporally instantiate types instance_of( x, U, t) → is_a( U, continuant)