  Pattern-based methods of IS-A relation extraction rely heavily on so called
Hearst patterns. These are ways of expressing instance enumerations of a class
in natural language. While these lexico-syntactic patterns prove quite useful,
they may not capture all taxonomical relations expressed in text. Therefore in
this paper we describe a novel method of IS-A relation extraction from
patterns, which uses morpho-syntactical annotations along with grammatical case
of noun phrases that constitute entities participating in IS-A relation. We
also describe a method for increasing the number of extracted relations that we
call pseudo-subclass boosting which has potential application in any
pattern-based relation extraction method. Experiments were conducted on a
corpus of about 0.5 billion web documents in Polish language.
