SWRL

// Family ontology rules in SWRL (Semantic Web Rule Language)
// Demonstrates inferring new relationships from existing ones

// Grandparent: if x has parent y, and y has parent z, then x has grandparent z
hasParent(?x, ?y) ^ hasParent(?y, ?z) -> hasGrandparent(?x, ?z)

// Uncle: if x has parent y, and y has a brother z, then x has uncle z
hasParent(?x, ?y) ^ hasBrother(?y, ?z) -> hasUncle(?x, ?z)

// Aunt: if x has parent y, and y has a sister z, then x has aunt z
hasParent(?x, ?y) ^ hasSister(?y, ?z) -> hasAunt(?x, ?z)

// Sibling: if x and y share a parent but are different individuals
hasParent(?x, ?p) ^ hasParent(?y, ?p) ^ differentFrom(?x, ?y) -> hasSibling(?x, ?y)

// Sibling symmetry
hasSibling(?x, ?y) -> hasSibling(?y, ?x)

// Parent inversion: hasParent implies hasChild in reverse
hasParent(?x, ?y) -> hasChild(?y, ?x)

// Adult classification by age
Person(?x) ^ hasAge(?x, ?age) ^ swrlb:greaterThan(?age, 17) -> Adult(?x)