@techreport{R-92-21,
PSURL = {/publications/cgi-bin/tr-fetch.pl?r-92-21+ps},
ABSTRACTURL = {/publications/cgi-bin/tr-fetch.pl?r-92-21+abstr},
ABSTRACT = {We consider the possibility of generalizing the
notion of a fuzzy If-Then rule to take into account its context
dependent nature. We interpret fuzzy rules as modeling a forward
directed causal relationship between the antecedent and the
conclusion, which applies in most contexts, but on occasion breaks
down in exceptional contexts. The default nature of the rule is
modeled by augmenting the original If-Then rule with an exception
part. We then consider the proper semantic correlate to such an
addition and propose a ternary relation which satisfies a number of
intuitive constraints described in terms of a number of inference
rules. In the rest of the paper, we consider implementational issues
arising from the unless extension and propose the use of reason
maintenance systems, in particular TMS's, where a fuzzy
If-Then-Unless rule is encoded into a dependency net. We verify that
the net satisfies the constraints stated in the inference schemes
and conclude with a discussion concerning the integration of
qualitative IN-OUT labelings of the TMS with quantitative degree of
membership labelings for the variables in question. A generalization
to the TMS relabeling algorithm is proposed which would permit the
modeling of reasoning with ``generalized modus ponens''.
},
TITLE = {Fuzzy If-Then-Unless Rules and their Implementa    tion},
AUTHOR = {Patrick Doherty and Dimiter Driankov and Hans Hellendoorn},
EMAIL = {patdo@ida.liu.se},
YEAR = {1992},
NUMBER = {R-92-21},
INSTITUTION = ida,
ADDRESS = idaaddr,
IDANR = {LiTH-IDA-R-92-21},
NOTE = {Extended Version of a Paper accepted at InternationalConference on Information Processing and Management of Uncertainty in Knowledge-Based Systems,  IPMU'92 Palma de Mallorca, July 6-10, 1992}