The APICP flag
keepeqvs lets you set the default for concept
expansion. If set on, unless otherwise marked, the search will use
any equivalences found in the Equivalence File associated with any
word entered in a query. This global condition can be selectively
reversed by preceding a word in a query with a
~ tilde. If the
global setting is off, the
~ will selectively enable
concept expansion (i.e., equivalence look-up) on that word; if
the global setting is on, the
~ will turn it off for that word.
(Note that equivalences can also be explicitly specified in
parentheses; see here.)
While use of the Equivalence File is an integral part of the
intelligence of a Metamorph search, in certain kinds of particularly
specialized or technical data such abstraction may not be desired.
keepeqvs flag off prevents any automatic lookup in the
Equivalence File, changing the nature of the search so that the
emphasis is rather on intersections of valid word forms of specified
English words, mixed in with special expressions. For example:
What RESEARCH has been done about HEALTH DRINKS?
Morpheme processing will be retained on the important (non-noise) words, but equivalences will not be included. An example of a sentence this question would retrieve, would be:
The company had been researching ingredients which would taste good in a drink while still promoting good health.
Where the global setting is on and you wish to selectively restrict
Equivalence Lookup on some but not all words, you use tilde `
in front of those words where no equivalences are desired. This would
be the preferred method of search for some types of technical
material, such as medical case data.
Although at first glance it would seem that an effective Metamorph search could not be done on technical data until much specialized nomenclature was taught to the Equivalence File, this is not always the case. Often a technical term means only that, and the power is in intersecting some valid English form of that word with some other concept set.
An example of a very discrete query that requires no knowledge
engineering beyond what comes "out of the box" with Metamorph might
be as in this query (assuming
keepeqvs turned on):
stomach ~cancer operation
The tilde `
~' is used to restrict equivalence lookup on
cancer" (toggle the
keepeqvs setting, to off), as
references to such things as "
illness" rather than
cancer" would be too abstract. However, what you do want is
concept expansion on the related words. Therefore, such a search
would retrieve the sentence:
Suffering severe pains in his abdomen, it was first thought to be appendicitis; however this led to exploratory surgery which revealed cancerous tissue.
In this example, "
cancerous" is a valid word form of
cancer" included through the morpheme process;
abdomen" was found because it was in the "
equivalence list; "
surgery" was found because it was in the
operation" equivalence list.
Again, with the
keepeqvs flag set on, use of the tilde
~) reverses its meaning. Therefore, the above example would
seek only valid word forms of the root words "
operation", but the tilde preceding "
selectively enable Equivalence Lookup on that word alone. So, with
keepeqvs off, we might retrieve instead the following:
In the midst of the operation to remove her appendix, an abnormal growth was found in the stomach area.
This last response is matched because "
stomach" are forms of those root words; "
in the equivalence list for "
cancer" and was included in the
set of possibilities due to the tilde (
~) preceding it.