Natural Language Processing

228 Natural Language Processing: Semantic Aspects

obtained at Semeval-2012 (Task 8, crosslingual TE) some notable

results (Perini 2012).

10.3.3 Two more examples of the comparison criterion

A cosine directional criterion

In (Tatar et al. 2009b) two cosine measures considering the words

of T = {t

1

, t

2

, . . . , t

m

} and of H = {h

1

, h

2

, . . . , h

n

} are defi ned. Since

usually n  m, let denote by

T



and

H



two vectors so that they have

an equal number of components:

• The two vectors for calculating cos

T

(T, H) are :

T



= (1, 1, . . . 1)

(an m-dimensional vector) and

H



, where

H



i

= 1, if t

i

is a word

in the sentence H and

H



i

= 0 otherwise.

• The two vectors for calculating cos

H

(T, H) are :

H



= (1, 1, . . .1) (an

n-dimensional vector) ...