Head-driven Phrase Structure Grammar I

Basic Idea Typed feature structure HPSG: First glance
Type hierarchy: Most general common subtype of two types
Definition
◮ For types τ 1 , τ 2 ∈ T , τ 1 and τ 2 are consistent if they have
a common subtype or an upper bound σ ′ , such that
τ 1 ⊑ σ ′ and τ 2 ⊑ σ ′ .
◮ A least upper bound σ (lub(τ 1 , τ 2 )) of τ 1 and τ 2 is defined
as follows:
◮ σ is an upper bound of τ 1 and τ 2 .
◮ For any upper bound σ ′ of τ 1 and τ 2 , σ ⊑ σ ′ .
dolphin elephan salmon
aquatic-animal terrestrial-animal mammal fish
animal
Weiwei Sun Head-driven Phrase Structure Grammar I 19/61