Sectorial Seaches
From TNT
Sectorial-searches are of two basic types: constraint-based and random; a combination of both is the mixed sectorial searches. Sectorial searches take a portion of the tree, create a reduced data set, and produce a mini-analysis of that data set. If a better solution for that portion of the tree is found, it is replaced back into the original tree. Every certain number of (user-determined) rearrangements, a round of global TBR is done (to insure global optimality). If the sectors are below a certain size, the mini-analysis consists of three RAS+TBR (random addition sequence wagner trees plus TBR); if the three sequences end up in trees of the same score, the mini-analysis is interrupted (i.e. the reduced data is "clean" and not worth of further analysis); otherwise, three additional RAS+TBR are done. If the sectors are above that size, a certain number of iterations of tree-drfiting is done to the reduced sector. The three types of sectorial-search differ in how the sectors are selected. Constraint-based searches choose the sectors by reference to constraints: the nodes that are resolved as polytomies in the constraint tree, connecting to no less than N branches (where N is some number defined by the user; default is 10). A reduced data sets corresponding to each of the polytomies in the constraint tree is analyzed, in turn; this is repeated a certain number of times (default=3), because changing some sector may imply that other sectors should change as well. Random sectors are chosen at random, to be no smaller and no bigger than a certain (user defined) size. The mixed sectorial searches use both constraint-based and random sectors; they can only be used with multiple addition sequences. For the mixed sectorial search, a temporary constraint tree is created by consensing the tree found at some stage of the present addition sequence (user defined: this can be the wagner tree, which is the default, or optionally the tree produced by SPR or TBR), and this constraint tree is used to do a constraint-based sectorial search. Once this is finished, a random sectorial search is done (unconstrained, or using only the user-defined constraints if they are in effect).
Path: Analyze/New Technology seach/Sectorial Searches
