Suppose that ? is a generic search ordering Using Lemma 6.3.1 on ?, we know that: ? is a generic ordering ?? for every x, y ? V (G), x < ? y, N ? (x, x) < gen N ? (y, x) ?? for every x, y ? V (G), x < ? y, N ? (y, x) = ? or N ? (x, x) = ? ?? for every x (x, x) = ? ?? for every triple of vertices a ,
for every triple a, b, c ? V (G) such that a < ? b < ? c and a is the leftmost vertex of N (b) N (c) in ? ,
Let us show that < LexU P (respectively < LexDOW N ) is an extension of < gen . Let A < gen B. By definition we have A = ? and B = ?. As a consequence we have (umax(A) < min, )) implying A < LexDOW N B) ,
By definition, we have umin(B) < umin(A) As a consequence ,
(v)) < GLS ?(l T BLS,i (w)), and l GLS,i (v) < GLS l GLS,i (w) if and only if for all l v ? ? ?1 (l GLS,i (v)) and all l w ? ? ?1 (l GLS,i (w)), l v < T BLS l w . Thus, the set of eligible vertices at step i is the same for both algorithms. GLS can pick any of these vertices, particular the one that would be picked by T BLS(G, < T BLS , ? ), and by setting ? to be equal to GLS(G, S), TBLS would indeed choose the right vertex ,
Computing a TBLS ordering Let P be the partition {V (G)}, where the only part V (G) is ordered with respect to ? ; for i ? 1 to n do Let Eligible be the part of P with the largest label with respect to < and x its first vertex; replace Eligible by Eligible ? {x} in P ; ?(i) ? x ,
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