@techreport{R-91-13,
PSURL = {/publications/cgi-bin/tr-fetch.pl?r-91-13+ps},
ABSTRACTURL = {/publications/cgi-bin/tr-fetch.pl?r-91-13+abstr},
ABSTRACT = {We present a non-monotonic logic with explicit defaults, NML3, characterized by
the following features: (1) The use of the strong Kleene three-valued logic as 
a basis. (2) The addition of an explicit default operator which enables 
distinguishing tentative conclusions from ordinary conclusions in
the object language. (3) The use of the idea of preferential entailment to 
generate non-monotonic behavior.

The central feature of the formalism, the use of an explicit default operator
with a model theoretic semantics based on the notion of a partial 
interpretation, distinguishes NML3 from most of the existing formalisms.
By capitalizing on the distinction between tentative and ordinary conclusions,
NML3 provides increased expressibility in comparison to many of the standard 
non-monotonic formalisms and greater flexibility in the representation of 
subtle aspects of default reasoning. We show this through example. 

Technically, NML3 belongs to the class of preferential logics. The semantics
is model-theoretic with well motivated underlying intuitions and is 
multi-valued. An explicit default operator is defined with an intuitive 
declarative semantics. We show (in the context of recent work by 
Makinson and Kraus et. al. that NML3's consequence relation is well-behaved.


},
TITLE = {NML3 --- An Non-monotonic Logic with Explicit Defaults},
AUTHOR = {Patrick Doherty and Withold Lukaszewicz},
EMAIL = {patdo@ida.liu.se},
YEAR = {1991},
NUMBER = {R-91-13},
INSTITUTION = ida,
ADDRESS = idaaddr,
IDANR = {LiTH-IDA-R-91-13},
NOTE = {To appear in the Journal of Applied Non-Classical Logics, 1991}