Asymmetric Similarity functions

Description

Compute various asymmetric similarities between words

Usage

1
asym(x,y,method,t=0,tvectors,breakdown=FALSE)

Arguments

x

A single word, given as a character of length(x) = 1

y

A single word, given as a character of length(y) = 1

method

Specifying the formula to use for asymmetric similarity computation

t

A numeric threshold a dimension value of the vectors has to exceed so that the dimension is considered active; not needed for the kintsch method

tvectors

the semantic space in which the computation is to be done (a numeric matrix where every row is a word vector)

breakdown

if TRUE, the function breakdown is applied to the input

Details

Asymmetric (or directional) similarities can be useful e.g. for examining hypernymy (category inclusion), for example the relation between dog and animal should be asymmetrical. The general idea is that, if one word is a hypernym of another (i.e. it is semantically narrower), then a significant number of dimensions that are salient in this word should also be salient in the semantically broader term (Lenci & Benotto, 2012).

In the formulas below, w_x(f) denotes the value of vector x on dimension f. Furthermore, F_x is the set of active dimensions of vector x. A dimension f is considered active if w_x(f) > t, with t being a pre-defined, free parameter.
The options for method are defined as follows (see Kotlerman et al., 2010) (1)):

Value

A numeric giving the asymmetric similarity between x and y

Author(s)

Fritz Günther

References

Kintsch, W. (2015). Similarity as a Function of Semantic Distance and Amount of Knowledge. Psychological Review, 121, 559-561.

Kotlerman, L., Dagan, I., Szpektor, I., & Zhitomirsky-Geffet, M (2010). Directional distributional similarity for lexical inference. Natural Language Engineering, 16, 359-389.

Lenci, A., & Benotto, G. (2012). Identifying hypernyms in distributional semantic spaces. In Proceedings of *SEM (pp. 75-79), Montreal, Canada.

See Also

Cosine conSIM

Examples

1
2
3
4
data(wonderland)

asym("alice","girl",method="cosweeds",t=0,tvectors=wonderland)
asym("alice","rabbit",method="cosweeds",tvectors=wonderland)

Questions? Problems? Suggestions? or email at ian@mutexlabs.com.

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