Designating Logic Operators (+) and (-)

Searches can be weighted by indicating those sets you ``must include'' with a plus sign (+) and those sets ``not to include'' with a minus sign (-). Those sets not so marked have the default designation of an equal sign (=), which means all such sets have an equal weight. The must include (+) and must not include (-) designations are outside the intersection quantity count; intersections are calculated based on the number of intersections of unmarked or equal (=) sets you are looking for.

In Metamorph terms we refer to an equally weighted set (=) as ``set logic''; a ``must include'' set (+) as ``and logic''; and a ``must not include'' set (-) as ``not logic''. These definitions should not be confused with Boolean terms, as although the definitions overlap, they are not identical. Traditional ``or'' logic can be assigned by using the ``@0'' designation on the query line, denoting zero intersections of the unmarked sets.

When a (+) or (-) set is designated, remember that it applies to the whole set; not just the word you have marked. Example:

     @1 disease blood skin +infection -bandaid

The above query specifying intersections at one (@1) means that you are looking for one intersection (@1) of anything from the set of words associated with ``disease'', ``blood'', and ``skin''; and of those hits, you only want those containing something from the set of words associated with ``infection''; but you would rule the hit out if it contained anything from the set of words associated with ``bandaid''.

You can designate any set entered on the query line as `+' or `-'; therefore this applies as much to wildcard (*), REX, XPM, NPM expressions, and macros, as it does to words. Example:

     power struggle -%70Raygun

This finds all references to power and struggle (and their equivalences) but filters out any references to 70% approximation to the pattern ``Raygun'' (i.e., it would omit references to hits containing the word ``Reagan'').

The important rule to remember about assigning `+' or `-' operators is that you cannot look for only minuses (-).

This chapter has attempted to cover the types of items which comprise a Metamorph query. Logic operators can be used to add special weighting to any of those things which will be viewed as single sets. Therefore you can assign a `+' or `-' to any of the types of query items that are described herein; and realize that with no other such marking, any search item is understood to be given an equal `=' weighting.