Toggling Equiv Expansion On or Off

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. Turning the 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 "stomach" 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 "stomach" and "operation", but the tilde preceding "cancer" would 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 "operation" and "stomach" are forms of those root words; "growth" is in the equivalence list for "cancer" and was included in the set of possibilities due to the tilde (~) preceding it.