Origen de la gestión por competencias

This section draws an example document from the Reuters collection to illus- trate the differences between representation schemes. Table 4.1 compares words and concepts that are frequently mentioned in Reuters document #15264, which discusses ongoing attempts by Teck Cominco—a Canadian mining company—to begin a joint copper-mining venture in Highland Valley, British Columbia. Word- Net concepts are sets of synonyms, and the subscripts of each WordNet term denote its part of speech—with 1 meaning nouns, 2 verbs, 3 adjectives and 4 adverbs—and commonness rank of the sense (see Appendix A). For example, the first synset in Table 4.1 refers to the most common sense of negotiation as a noun

4.4. EXPERIMENTAL RESULTS

Document TECK STILL IN TALKS ON B.C. COPPER VENTURE Teck Corp said it was

continuing talks about joining a joint copper venture at Highland Valley, British Columbia, held by affiliates Cominco Ltd CLT and Lornex Mining Corp, but did not know when negotiations would be completed. Teck vice-president of adminis- tration John Guminski said in reply to a query that the talks had been “ongoing for a long time.” He declined to speculate on the outcome. Cominco, 29.5 pct owned by a consortium led by Teck, is optimistic that the talks will soon be concluded, spokesman Don Townson told Reuters. “I think all partners are hopeful that the situation will be resolved,” Cominco’s Townson said. “We’re optimistic that they will be concluded shortly,” he added. Townson declined to specify when the talks might end. Cominco and Teck’s 22 pct-owned Lornex agreed in January 1986 to form the joint venture, merging their Highland Valley copper operations. Cominco and Lornex share equally in control and management of the Highland Valley op- erations, while Cominco has a 55 pct share of production and Lornex receives 45 pct. For the six months following July 1, 1986, when the venture officially started production, Highland Valley had total ore milled of 22.6 mln short tons, grading an average of 0.41 pct copper, Townson said. Cominco’s share of production was 43,000 short tons of copper contained in concentrate, 1,200 short tons of Molyb- denum in concentrate, 340,000 ounces of silver and 800 ounces of gold, he said. A consortium, 50 pct owned by Teck and 25 pct each by MIM (Canada) Inc and Metallgesellschaft Canada Ltd, acquired its Cominco stake last year from Canadian Pacific Ltd CP.

Features (total

number) Most frequent 20 features

Words cominco (8) pct (7) teck (6) copper (5) talk (5)

(77) vallei (4) ventur (4) product (3) share (3) short (3)

ton (3) canada (2) concentr (2) conclud (2) consortium (2)

corp (2) declin (2) joint (2) oper (2) silver (1)

WordNet {negotiation11, dialogue14, talks16} (6) {copper11, Cu11, atomic number 2911} (5) concepts {percentage11, percent11, per centum11, pct11} (5) {valley11, vale11} (4)

(83) {venture11} (4) {share11, portion14, part18, percentage12} (3)

{production11} (3) {short31} (3) {short ton11, ton11, net ton11} (3)

{Canada11} (2) {joint31} (2) {optimistic31} (2)

{upland31, highland31} (2) {worsen21, decline21} (2)

{operations12, trading operations11} (2) {own21, have24, possess12} (2)

{consortium11, pool14, syndicate12} (2) {reason21, reason out21, conclude21} (2) {ounce11, troy ounce11, apothecaries’ ounce11} (2) {dressed ore11, concentrate11} (2)

Wikipedia Teck Cominco (9) Teck (6) Copper (5)

concepts Canada (3) Short ton (3) Product (business) (2)

(27) British Columbia (2) Ounce (2) Consortium (2)

Mining (1) Joint venture (1) Ore (1)

Pacific Ocean (1) Gold (1) Silver (1)

Metallgesellschaft (1) United Kingdom (1) Molybdenum (1)

Negotiation (1) Partnership (1)

Method Concepts identified Gabrilovich and

Markovitch

Teck; John Townson; Cominco Arena; Allegheny Lacrosse Officials Association; Scottish Highlands; Productivity; Tumbler Ridge, British Columbia; Highland High School; Economy of Manchukuo; Silver; Gold (color); Copper (color);

Hu et al. Tech Cominico; British Columbia; Mining; Molybdenum; Joint

Venture; Copper

Table 4.2: Wikipedia concepts identified by other approaches

is also the fourth and sixth most common sense of dialogue and talks (denoted by

dialogue14 and talks16 respectively).3

All the representation schemes are able to pick up on the different minerals and units—copper, silver, ounce—and the concept-based ones explicitly relate them to synonyms such as Cu and oz. WordNet fails to note specific named entities such as Teck Cominco, but identifies terms such as complete that do not resolve to Wikipedia articles. It is quite clear from Table 4.1 that Wikipedia concepts are much more succinct than both words and WordNet concepts from the human point of view. This is a helpful characteristic for generating descriptions of clusters. Although the issue of describing clusters is not investigated in this thesis, it has been shown that users prefer a more informative representation than a simple list of the most frequently occurring keywords in the cluster (Harper et al., 1999). Wikipedia concepts, as shown in Table 4.1, are appropriate for this task.

Table 4.2 summarizes concepts identified from this document by two other

Wikipedia-based approaches.4 This presents an intuitive comparison of our method

(see Table 4.1), implemented in the Katoa toolkit, with related work. The first is the full-text-based method of Gabrilovich and Markovitch (2007), described in Section 4.2, which gathers Wikipedia concepts by measuring term overlap with the given text. This unfortunately allows unrelated concepts such as Scottish Highlands and Economy of Manchukuo to creep into the representation. Also,

3_{The meaning of a WordNet synset or a Wikipedia concept can be retrieved by using}

WordNet’s online search interface at http://wordnetweb.princeton.edu/perl/webwn/ and by searching for the concept’s name in Wikipedia at http://en.wikipedia.org.

4_{Results for these two approaches are taken from Hu et al. (2008), which are part of the}

4.4. EXPERIMENTAL RESULTS

this method performs disambiguation only indirectly, which introduces more ir- relevant concepts such as Copper (color).

Both Hu et al. (2008)’s system and Katoa produce the tightest representation of a document, because they only contain the Wikipedia concepts that it discusses. Nevertheless, both are able to expand out from these concepts to consider their related ones, and thus connect texts with similar themes regardless of their textual overlap—or lack of it. For example, when computing the similarity between two documents, Hu et al.’s system considers broader topics mined from the categories to which each article belongs and associated topics mined from the links extend- ing out from each article. Thus Teck Cominco can be augmented with Mining companies in Canada and Con Mine (Hu et al., 2008). Katoa’s representation models can also be expanded (as Section 5.4 will show): a concept such as Teck Cominco could be expanded on demand with a huge pool of possibilities, such as different mining companies (Codelco, De Beers, and about a hundred others), tools (Drilling rig, Excavator, etc.) and locations (the Pebble Mine in Alaska, for example). The flexibility allows them to compete with models already expanded with concept relations.