ase, one substitution is required.</span> are eliminated from the computation of their <i>L</i> 
 values. Thus while the algorithm speeds up the search for the MP tree, 
 as compared to the branch-and-bound search, the final tree or trees may 
 not be the true MP tree(s).&#160;&#160;The user can specify a search factor 
 to control the extensiveness of the search and <i>MEGA</i> adds the user 
 specified search factor to the current local upper bound.&#160;&#160;Of 
 course, the larger the search factor, th