文档介绍：Some Direct Theories of
Nonmonotonic Inheritance
John F
Hort y
Con ten ts
In tro duction
Bac kground
Ov erview
Basic concepts
Theories of defeasible inheritance
Defeasible inheritabilit y
Constructing extensions
Theories of mixed inheritance
Strict inheritabilit y
Mixed inheritabilit y
Constructing extensions
Discussion
Decoupling and stabilit y
V arieties of preemption
A
xedpoin t approac htosk eptical inheritance
T ranslational theories and meaning holism
Implemen tational concerns
A Pro ofs of selected theorems
In tro duction
Bac kground
Inheritance systems w ere originally dev elop ed within arti
cial in telligence
in resp onse to the practical need for an e
cien tw a y of represen ting and
accessing taxonomic information
These systems
along w ork rep
John F
Horty
resen tations more generally
w ere
rst presen ted without an y seman tic anal
ysis at all
or else only with a pro cedural seman tics
according to whic hthe
meaning of the represen tations w as supp osed to b e sp eci
ed implicitly b y
the programs op erating on them
Ho w ev er
in large part due to the crit
icisms of W o o ds
a go o d deal of atten tion w as so on dra wn to the
problem of supplying an implemen tation indep enden oun t of the mean
ing of w ork formalism s
Most of the w ork on this problem
and
notably that of Ha y es
follo w ed a translational or indir e ct strategy
sp ecifying the meaning of w ork formal