for query expansion could result in retrieving documents involving advice (one sense of

counsel) and royalty (as one sense of court).

$$c o u r t\quad13$$
Resnik (1998a) introduces an algorithm that uses taxonomically-dened semantic similarity in order to derive grouping relationships among word senses from grouping relation-

$$\begin{array}{l l}{\mathrm{N}}&{\qquad}&{a t t o r n e y}\\ {\varphi}&{}&{}\end{array}$$
$$W$$ $$a t i o r n e y$$
$$c o u n s e l$$
attorney, counsel, trial, court, judge.

as

$$t r i a l$$
a lawyer who pleads cases in court.

legal proceedings consisting of the judicial examination of issues by a competent tribunal

$$c o u r t$$
the determination of a person's innocence or guilt by due process of law.

an assembly to conduct judicial business

a room in which a law court sits.

$$\langle\varphi\rangle$$
a public ocial authorized to decide questions brought before a court of justice.

associated with the group to a lesser extent or not at all. These would include the sense of

direction or advice as to a decision or course of action;

word sense ambiguity in information retrieval.

$$j\,u d\,g e$$
$$c o u r t$$
111
ships among words. Formally, the problem can be stated as follows. Consider a set of words W fw1; : : : ; wng, with each word wi having an associated set Si fsi;1; : : : ; si;mg of pos- sible senses. Assume that there exists some set W0  S Si representing the set of word senses that an ideal human judge would conclude belong to the group of senses correspond- ing to the word grouping W (It follows that W0 must contain at least one representative

$W$$W^{\prime}$$\varphi$$s_{i,j}$$w_{i}$$s_{i,j}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$$W^{\prime}$$\mathrm{N}$\(
$$\begin{array}{c}{{S_{i}}}\\ {{W}}\end{array}$$

precludes the possibility that multiple senses of a word are included in W0
For example, consider again the group

Restricting attention to noun senses in WordNet, every word but attorney is polysemous.

Treating this word group as W good algorithm for computing ' should assign value
of 1 to the unique sense of attorney, and it should assign a high value to the sense of counsel

Similarly, it should assign high values to the senses of trial as

It should also assign high values to the senses of court as

And it should assign a high value to the sense of judge as

It should assign low values of ' to the various word senses of words in this cluster that are
counsel as

similarly, a low value of ' should be assigned to other senses of court such as
13. See Krovetz and Kroft, 1992 and Voorhees, 1993 for experimentation and discussion of the eects of
