In order to score a CM model the inside-outside algorithms are used. CMs use a slightly different implementation of CYK. Log-odds emission scores for the optimum parse tree - formula_38 - are calculated out of the emitting states formula_39. Since these scores are a function of sequence length a more discriminative measure to recover an optimum parse tree probability score- formula_40 - is reached by limiting the maximum length of the sequence to be aligned and calculating the log-odds relative to a null. The computation time of this step is linear to the database size and the algorithm has a memory complexity of formula_41.