Báo cáo khoa học: "SOLUTIONS TO ISSUES DEPEND ON THE KNOWLEDGE REPRESENTATION" ppt

SOLUTIONS TO ISSUES DEPEND ON THE KNOWLEDGE REPRESENTATION

F r e d e r i c k B T h o ~ p s o H

~ l i £ o r n i ~ I n s t i t u t e o£ T e c h n o l o g y

P a s a d e n a , C ~ , l i ? o r n i ~

In o r p Q n i z i n g This p ~ n e l , our

Ch(tirmon, Bob Moore, expressed the view

t h o r t o o o f t e n d i s c u s s i o n o? H o t u r r a ' l

l,',nguage o c c e s s To dol'o b u s e s h a s f o c u s e d

on w h o t p ~ r t i c u l c ~ r systems c~*n o r c Q n n o t

d o , r o ' t h e r t h a n on u n d e r l y i n g i s s u e s He

T h e n s d ~ i r r 4 b l y p r o c e e d e d t o o r g o n i z e t h e

p r J n e l nr o u n d i s s u e s r-qther th~n s y s t e m s

In r e s p o n d i n g , I q t t e m p t e d to ?rr.iMe my

~'emr~rk~, on e,ach o? h i s f i v e i s s u e s in r~

g e n e r ~ l woy that w o u l d not r e f l e c ~ ~y ,wn

p r 4 r o c h i u l e x p e r i e n c e qnd i n t e r e s t , At one

p o i n t I t h o u g h t th~.~t I h~d s,cceeded q u i t e

w e l l Howe,.,er~ o f f e r t ~ k i n g a c l e o r e r eyed

v i e w ~ it w q s q p p a r e n t t h o r my r e m a r k s

reflec~c;d ~ s s u m p t i o n s o b o u t k n o w l e d g e

r e p r e s e n t o t i o n t h e f t were b y no M e o n s

univers~ol T h i s s u g g e s t s ,a s i x t h i s s u e

which I would l i k e ~o r ~ o m i n ~ t , , :

Are t h e r e r ' e o l l y u s e f u l g e n e r o l i z N t i o n s

~bou~ comput~Jtionr~l l i n g u i s t i c issues

th<~t c~r,e i n d e p e n d e r ~ t o f r ~ s s u m p t i o n s

c o n c e r n i n g knowledq,.~ r ' e p r e s e n t c i t i o n ?

I w i l l c o m e b a c k 'to this s i x t h issue

q ? t e r d i s c u s s i n g t'i~e ?ire cho-~.,n b y our

C h o i r ~ o r ,

I ~s~,e @i : A.q.ctreq~te_ F.~nc.t i o ns qnd ~uon.!i.S.~

F ' i r s t ~ l e t us csst t h i s i s s u e i n o

~ o m e w h o t d i f f e r e n t w a y , I r l m~.sny d~tc, b~se

~:ituo.1io~s., t h e r e ,',r'e c l o s e s of

i n d i v i d u a l s o l I o f w h o s e Me~bers shcire the

~.:oMs o t ' ~ r i b u t e s ~and thus, ÷'rum the p o i n t

of view o.f the dr~'t~ bose~ ,ir~

.~.ndi~tJ,vuish,~ble 'Thus t h e r e i s no need

~o ~dd ,*II o f the~.~ , i n d i v i d u a l s Qs

~':.e prw, o't(~ e n t i t i e s , To use Bob M o o r e ' s

Cur NUMPER"OF-EMPL.OYEES~ i t strands To

r'~~,.~on th~L~' the pczr!icul~:~r [ndividu~.~Is ;~ho

~ c ~ u o l l y e x i s t e d in the v,ar'ious

dep~r't~tHH~'~ w o u l d r~o~ be s~ep,ar,~tely

r'~pr'e,>~:~,~ed i n the dc~~obose (for u t h e r ' w i s e

t h e r e would be o redund,.~ncy whose

, :or1~J'-.:'~.;nc,./ would be h~r'd to p o l i c e ) , In

~u,-'h :~i~u,:~io~s we n e e d the n o t i o n o f ~'~

" , ~ o l l e L ' t i , ~ e , " homely ~a s i n g l e dr~tr~ b,ase

, ' ~ d d i t i o n , i l i t e m o? i n ~ ' o r m o t i o n , n o m e l y

~ h e i r r~umber, Thus ~ DEPARTMENT c o u l d h~ve ~s o s i n g l e ~ember su,:h ~ c o l l e c t i v e ,.,f employees, indeed i t c o u l d hove severQl such c o l l e c t i v e MeMbers ond o t h e r

i n d i u i d u ~ l MeMbers ~s w e l l The p r o c e d u r e

t h o r i s c~11ed when onswering "how Mony"

~nd "nu(~ber o f " q u e s t i o n s would know the

d i f ? e r e n ( - e between subcl~s,~es, i n d i u i d u r J l (~eMber~ r~nd c o l l e c t i v e ~ e m b e r s ~ it w o u l d

k n o w t o r e c u r s e on s u b c l c ~ s s e s , ~.~dd o n e t o

i t s coun'~ f o r i n d i v i d u a l M e M b e r s o n d o d d

t h e indicoted' number" t o its c o u n t - f o r '

c o l l e c : t J v e MeMbers T h i s ~ppe~rs To be

u n i ? i e d ?r,~ework th,,t w i l l h(1~d].e ,~11 o f

t h e c:~s,e~ m e n t i o n e d i n Bob M o o r e ' s

s t Q t e m e n t o? Issue # I

I s s u e '~2: T,,iM,e, qnci T_e_p._s_e

I should l i k e to s p l i t t h i s issue i n t o two, The ? i r s t s u b - i s s u e i s the problem of

h o n d l i n g c o n t i n u u s l y v a r y i n g p h e n o M e n o >

~.~uch ra,:, 1he M o v e M e n t o f s h i p s ~ t h e chqnging o f relotiv,., ~zMount,:~ o f

i n g r e d i e n t s in c h e ~ i c ~ l r e Q c ~ i o n s ~ or "the

p e r c e n t c o m p l e t i o n s o9 t n s k s , H e r e i t i s

~pp(~rent thr~t eoch i n s t o n c e will r e q u i r e s

~ p e c i ~ l i z e d p r o c e d u r e to hKLnflle

i n t e r p o l , ~ t i o n Ships cr~nnot s ~ i l Qcross Irjnd~ t h u s ~n i n t e r p o l a t i o n procedure t h o r

p r o d u c e ~ t h e p o s i t i o n o f o s h i p on The bdJsis o f its p o i n t s o~' d e p ~ u ' t u r ~ , o n d des'tinotJ, orl w i l l need To know obout the c0cAstlines o? c o n r i n e n t s ~ M o v e m e n t s to cheMJ.c~l e q u i l i b r i u m s ~re not l i n e ~ r ~ t~sk coMpletioNs depend on changing p e r s o n n e l ossignf~ents Just rls we c o M p u t o t i o n o l

l i n g u i s t s p r o v i d e t o o u r s y s t e ( , ~ u ~ e r t h e ( o p o b i l i ' ¢ y t o i n t r o d u c e i n t o h i s d o t r ~ b ~ s e

s y s t e m ~ u c h n o t i o n ' ~ ,a~ l o c , = r i o n s of" port.~ end s h i p ~ , e t c > we Must ,also p r o v i d e ~he Met:ins by which he crarl d e f i n e such

' : o n t i n u o u s l y v r ~ r y i r ' , ~ p , a r ( ~ m e t e r s r~s

p o s i t i o n i n s u c h w q y s th~.~t ~ t p p r o p r J o t e

i n ~ e r p o ] , ' , t i o n s c~zn be ~ d e by ~he g e n e r o l

s y s t e m i n c o n j u n c t i o N w i t h t h e p , l r t l c u l o r

d e f i n i ' t J o n For" example, 'the user mr~y

d e ? i n e ~ " p o s i t i o n o? X " i n t e r ~ o f ( ' r ~ l c u ] : ' ~ % i o n s , p e r h o p s e x t e n s i v e > i n v o l v i n 9

The s e c o n d s u b - i s s u e on w h i c h I w o u l d

l i k e t o coMmen~ c o n c e r n s ~ h o s e c ~ s e s

where d i s c r e t e ~ime i n t e r v a l s p r o v i d e rin

r.~dequ(l~(~, r, e p r e s e n t r ~ t i o n o@ "(he t i m e

a s p e c t s r e l e v r , n t to t h e d a ' t q b q s e I n

*hese coses~ if` ~he t i m e i n f ` o r f ~ t i o n i s

coMplete~ i,e,, r i c t u ( : l st~Ir~lng ~nd e n d i n g

rimes of` rill e v e n t s ripe r e c o r d e d i n ~he

d ~ t Q b,~se, the h ~ n d l i n g o? time is rrither

strriightforwrird, H o w e v e r t h i s c ~ s e of"~en

d o e s n o t ripply, C o n s i d e r the ? a l l o w i n g

e xQmp], e :

"The Ki~tyhriwk ~ r r i v e d in L o n d o n M o n d a y ,

The Mriru w i l l s o i l ? r a m L o n d o n F r i d a y

W i l l th~ K i t c y h o w k ~nd Hrir'u h ~ v e b e e n in

L o n d o n ~t the s ~ e t i m e ? "

One i s teP~pted ~o o l l o w the c o m p u t e r

l o g i v e q r e s p o n s e : " P o s s i b l y , " however

the i n t r o d u c t i o n of` a t h r e e uolued l o g i c

i s Tr'qught w i t h w e l l known d~ngers of" i t s

o w n , A More p r o t r r i c t e d r e s p o n s e g e t s i n

t h e way o~ c l n u s e [ ~ b e d d i n g ; how d o e s one

hrind].e~

" W i l l s i ~ i p s t h r i t have been i n L o n d o n

t o g e t h e r sriil t o g e t h e r ? "

One r i n s ~ e r w o u l d be:

"The Ki~i'.vh~.~wk r i r r i v e d IriF~t Mondc~y~

the Mor, u will soil n e x t F r i d a y , I~

t h e y will hrive b~.en t h e r e q t the same

London t o g e t h e r w i l l s r i i l 1'ogether~ bu~

t h e y v:ould be the only e x c e p t i o n s , "

C h o o s i n g ~ r e l e v ~ m t d i c ~ g n o s t i , :

t,eessoge~ o s o b o v e , i s o M r i j o r r~nd

d i £ ? i c u l ' t c o M p u t o t i o n , : ~ l l i g u i s ~ c i s s u e

(:~oing w~],l b e y o u n d q u e s t i o n s c o n c e r n i n g

t i M e ~lII,J *,ense,

Issue %3 : _~_~r.ULi.f,,.! i.]:Lg ~,p_xo ~u.esx i o n s

T h i s i ~ a deep~ p h i l o s o p h [ c , l l

pr, o g r w : s ~ e d b e y o n d tl'w , : o n s i d e r q t i o n o?

, ? o l l o w ~che ' f o c u s o f ,] d i r j l o g u ~ ~ (And

i d e n ' t i f y 'the theme o? ~ d i s c o u r s e , T h i s i s

ev~.r}~uqlly ,4n i n f i n i t e r e g r ' e , ~ u l t L M r i t e l y

i n v o ] v i ~ g c r o s s c u l ~ ' u r ~ l b r i c k g r o u n d s , ~he

( p e r h ~ / p s Mc, c h i c l v e l l i o n > irlt,~.n~ o~ t h o s e

,.,,ha co~,trol ~he u'~e oT o p a r t i c u l a r

:Jse£u] "~.o ~'he use.r? Consider kwo p o s s i b l e

( n ~ s w e r s ~o ,.'he F o l l o w i n g q u e s t i o n :

"Who ,.~on,.'~ges ec~cl~ d e p o r t m e n t ? "

Ai: "No s i n g l e p e r s o n M~nages ~ l l o~

t h e d e p o r ~ M e n t s , "

d e p t A ~ r i n ~ g e r A

U n l e s s ~ h e r e w e r e ~n undue n u m b e r o~"

d e p ~ r t M e n t s i n v o l v e d ~ t h e s e c o n d i s (.Ice, Ply prei~erred~ ?or it ~uf`f`ices "even i? the f ` i r s t were i n t e n d e d , I our own

e x p e r i e , c e , "e~ch" con u s e f u l l y be

i n ' t e r p r e t e d ,~s c o i l i n g ~ o r ~, l~b~.led l i s t ,~s onswer i n ~ l ~ o s t o l l c o s e s , The

d i f f " i c u l ¢ i e s of" b e i n g t~ore c l e v e r o r e

g r e a t arid will o~°ten r e s u l t i n

c o M b i n q t o r i ( l l e x p l o s i o n , I (~M s u r ~ , for o ]ong tJi~e into the f u t u r e , we will be

s e e k i n g s i m p l e s o l u t i o n s t h a t (?.~) o r e respon,~,ive i n M o s ~ c(~ses> (b) p r o v i d e the needed inforMr~eion~ even though r e d u n d ~ n t

Jn SOMe cGse~ rind ( c ) M~ke c : l e r i r the

M i s i n t e r p r e ~ r i t i o n in the £ e w c,~se where

t h i s r i r j s e s , e v e n t h o u g h t h e s e s o l u t i o n s

I s s u e #4 : ~4e_.,r vi.n~ ~.eM~n~ ic~.!_l y_ CoMp ke X

I n p r e s e n t i n g i~his i s s u e I o the prlnel~ Bob Moore used the ? o l l o w l n g t h r e e

q u e s t i o n s ris ~n example:

" I s John J o n e s (, c h i l d oF rln HIT

r l l U MIIU ~- ? "

" I s one o£ John ~ o n e s ~ s p ~ r s n t s on H I T ( l l u~)n u.~ 9"

" D i d e.i'~her p o r e n ~ o~" / o h n ] o n e s t~ttend

H I T ? "

po.~sibilit~,, of" M u l t i p l e d e s ( - r L p t i o n s ~

o ~ ' t e n i n v o l v i n g d i s p o r ' r i t e words~ For,

g e t t i n g ~lt dril:t, i n ~he d a t r i h~se, I n (.JeBicjrlillg our" s y s t e m s ) we r e c o g n i z e two

t r u ~ h ~ which ~ppe,~r' t o c o n , f l i c k : ( q ) t h e

v ~ l u e o.F M i n i M i z i n g the reduhdrincy o£ .LnforMf~tion i n the dqt(t b,1~e ( b ) the

n e c e s s i - i y o£ n o n - i n d e p e n d e n t w o r d s in the

you k n o w , we h o v e s t r e s s e d t h e use o?

d e f i n i t i o n s c~s u Me~zns o f ,'Ich.i.eving o

r e c o M M e d it to you u~ ri v~.r~ o~p.i~ul t o o l

in h o n d l i n o p r o b l e m s like B o b p r e s e n t s We

i l l u s t r a t e h o w B o b ~ s excLMpl~; c,.~n be hr~ndled :

" d e ' f i n i ~ i o n ' c h i l d : c o n v e r s e o~" p a r e n t ve.rb:John ",;it~end"~ H I T m J o h is '.-'tud~.t,~ o? HIT

dei'~inition:~lu~,r-'s'person w h o hod

b e e n ~ s t u d e n t "

The ubove t h r e e q u e s t i o n s t h e n ore

?.~n~1 y zed ~s:

"3"ohn ) o n e s i s ( c o n v e r s e o? p a r e n t ) o? a

p e r s o n who had been ~ s t u d e n t of H I T ? "

"One of ~ohn / o n e s ' s p a r e n t s i s a p e r s o n

who had b e e n a s t u d e n t o-t H I T ? "

"W~s e i ' t h e r p a r e n t o£ ~ohn ~ones a

s t u d e n t o f H I T ? "

I do not w i s h to slur' over' the f a c t

that ~.= d e f i n i t i o n Mech~.,nisM ~ust be h i f h l y

:sophis~'~coted i n i ~ s h a n d l i n g of f'ree

v a r i a b l e s , , bu~ our ~xperience i~dic~*te.~

tha~ ~l'~s can be done q u i t e

s ~ t i s f a c t o r i l y

I s s u e #5: H u ~ t i - F i l # _ ~ u e r ' i e _ s

T h i s i s s u e h a s b e e n s t a t e d by Bob in

t e r m s of G tr'~dixional M u l t i p l e f i l e de=to

b,~se s ' t r u c t u r e , T h i s i s s u e h~s i t s

c o u n ' t e r ' p ~ r t in seM~intic neT d a t a base

s t r u c t u r e s d i s c u s s e d in pr4per,~ on

k~ow].edge r e p r e s e n t a t i o n , Since we use

such q semantic net s ~ r u c t u r e For, our

d a t a , le't me rephrase the issue i n those

~erMs In Dab's st~tteMerlt of the issue~ he

uses tl'~ example o f the SHIP f i l e and the

PORT File; wl}ere the SHIP f i l e h,~s f i e l d s

-For ho~,~¢ p o r t , departure p o r t and

d e s t i n a t i o n p o r t P,~,r'allelLnq h i s

exa~p](:, l e t us c o n s i d e r ~h~ p h r a s e :

" L o n d o n s h i p " , Suppose ~hr.~t ( q ) there w~s

s h i p n,~r~ed L o n d o n , nnd ( b ) L o n d o n was a

h o ~ e por~, p o r t o f d e p q r t u r ~ and

d e s ' t i r ~ o ' ~ i o n ~ n o t n e c e s s a r i l y o~" t h e same

s h i p , Then " L o n d o n s h i p " i s f o u r w a y s

,~Mbifuous~ ~ e ~ n i n g : (i) t h e ship L o n d o n ~

(2) L o n d o n (ho~e p o r t ) s h i p s , (3) l.ondon

(depr~r~-ur~z par-X) ~hips ~nd (4) London

( d e s t i n q ~ i o n p o r t ) ~ h i p s , I n t h i s

f o r ~ u l ~ t i o n of t h e p r o b l e M ~ ~II i s easy~

i n s o f a r ~ the phr~s~; " L o n d o , ship" is n o t

'.iisc~Mbigu~Ted in c o n ' t e x t ~ t h e u s e r i s

i n f o r m e d o? t h e ~ l M b i g u o u s M ~ l r l i n c j s (Ind t h e

,~ssoci,:~'ted r e s p o n s e s The d i f f i c u l t y

.i.nterpr,.'<'~'ations ?,~r~her (~field, F o r t

C o l l i n s is n,.~.itl')er ,~ p o r t nor ~ s h i p ~

h o w e v e r ~.he headqunr'ters of t h e ABC

S l l i p p i r t , # CoMpany i~ t h e r e un,:l t h e y own

"For"t C o l l i n s .~hip"? The.~e ~u-e pr'obleM~

tha't wer.e ? i r s ~ ~1'*:acked by Q u i l l i c m , and

f qM n o t ~ur'e ~'t~(~'t u n y o n e I ~.~ c~dded to h i ~

we he*re s~uppecJ a t " o n c e re~-1oved"

,.:onnec.'tJons., ,:~ il].u~r~zTed by t h e f o u r -

Issue ~6: Solution~ tO Is~q.es_._D~.~.n

As I look back on the a b u v ~ r e M o r k ~ t:oncerning Sob's five issues~ i t becomes

~ p p a r e n t thr~t t h e u ~ e f u l n e s s of t h e s e

o f t h e knowledge r e p r e s e n t a t L o n t h a t

u n d e r l i e s t h e s o l u t i o n s u g g e s t e d , F o r

one only knew about t r a d i t i o n a l f i l e

s t r u c t u r e s ~ f i n d i n g paths theft l i n k f i e l d s

i n More Than one f i l e appears a l l b u t

u n s o l v a b l e , Even if one i s a c c u s t o m e d t o

s e m a n t i c n e t s t r u c t u r e s ~ the v i a b i l i t y of

f i n d i n g c o n n e c t i v e pnth.~ i s h i g h l ~ dependccn~ on t h e e x i s t e n c e of back l i n k s between a t t r i b u t e s and t h e i r ,~rgu~en~s and

v a l u e s A d d i n g a d e f i n i t i o n a l c a p a b i l i t y ~

o t h e r thun s i m p l e a b b r e v i q t i o n s ~md synonyf4s~ B u r n s on t h e way free v a r i a b l e s ore handled in 9ener~Jl cmd on t h e

opporo.tus +'or b i n d i n g theM) f o r example,

i n processing the d e + ' i n i t i o n :

" d e i ~ ] n i t i o n : a r e ~ : l e n g t h times w i d t h "

w h e n a p p l i e d ~o q c l a s s > say " a r e a s of

;~hips", h o w d o e s one e n s u r e ~ h a t he w i l l

ob rain :

" l e n g T h ( i ) ~k w i d t h ( i ) fop i = I to number o f s h i p ~ "

r a t h e r T h o n l

" l e n g T h ( i ) ~ w i d t h ( j )

? o r i~j = i to nut.~ber o? ship =.?"

It c o M e ~ d o w n to h o w v a r i a b l e s qre MainTained in The u n d e r l y i n g knowledge

r e p r e s e n ' t a t i o n ,

O n e i s £or'ced t o c o n c l u d e ~ h a t t h e

b a s i s ~'or t h e i n t e g r c l t i o n o f t h e s y n t a x cu,d ~ e m o n T i c s o? coMput,~tionr~l l i n g u i s t i c

s y s t e m s i~ - c c o M p l i s h e d wh n t i l e d¢ci~4ion~ on k n o w l e d g e r ' e p r e ~ e n ~ t i u n ~r'e Made, D i ~ J c u s s i o n s 0£ # u r w:~rLous sotut.En.n

to ~he J ~ s u e s of c o M p u t a T i o n a l l i n g u i s t i c s

c a n M e a n i n g f u l l y ~uke pl<~ce only in terM~

uf the,:,~ u n d e r l y i n g k n o w l e d g e repr'eser~tot ions