Complete r-ary patterns, non-fringe embeddings and leaf-height

Definitions of Sections 1.3–1.4 and 2.1 of the paper (source lines 464–473, 525–531, 682):

• completeTree r k is the complete r-ary tree H_{r,k} of height k;
• Embeds T' T is the relation T' ≺ T: T is obtained from T' by grafting arbitrary plane trees onto the leaves of T'. Internal vertices of T' keep their exact number of children (this is not "choose some children");
• maxCompleteHeight r T is H_r(T) = max {k ≥ 0 : ∃ u ∈ T, H_{r,k} ≺ T_u};
• rootLeafHeight T is λ_∅(T), the distance from the root to the closest leaf descendant (zero for a leaf), and leafHeight T = max_v λ_v(T).

All five are defined in PoissonDeclumping.Statements.Defs (namespace PoissonDeclumping.PlaneTree), which originate in the upstream statement contract; this module only re-exports them under its historical name.