L = { : t ∈ L(M) and s ∉ L(M), t,s ∈ {a,b}*, where t is the string after s in a lexicographic ordering of {a,b}*}.

 L = { : t ∈ L(M) and s ∉ L(M), t,s ∈ {a,b}*, where t is the string after s in

a lexicographic ordering of {a,b}*}. As examples, which must not appear in your proof: Let

L(M₁) = {b,aa}. Then ∈ L because b ∈ L(M₁) and a ∉ L(M₁); ∉ L because both

aa and b are in L(M₁); and ∉ L because a ∉ L(M₁). Prove that L ∉ D using a reduction

from H. Do not Rice’s theorem.