# 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.