“…For instance, ⟨a, b c d, e ⟩ ⊙ ⟨y 1 , y 2 , y 3 , y 4 ⟩ = ⟨a, by 1 cy 2 d, y 3 ey 4 ⟩. Simple external contextual (sec) languages are important mildly context-sensitive languages in the context of grammatical inference [4,19,2]. For p ≥ 1 and q ≥ 0, a p, q-sec grammar G over Σ is a pair ⟨B, C ⟩ where B ∈ (Σ * ) ⟨p⟩ and C ⊆ (Σ * Σ * ) ⟨p⟩ with |C| ≤ q.…”