INTERFACILE: Linguistic Coverage and Query Reformulation

I N T E R F A C
I L E
Yvette
:
Linguistic
Coverage
Mathieu
and
Paul
Query
Reformulation
Sabatier
C N R S - LADL,
Universit4 Paris 7
Tour Centrale 9 E
2 Place Jussleu
75005
Paris
I.
INTRODUCTION
-
T h e e x p e r i e n c e w e h a v e g a i n e d in d e s i g n i n g
[3,6,7] and using natural lanauage
i n t e r f a c e s h a s led us to d e v e l o p a g e n e r a l
natural language system, INTERFAC[LE,
involving the following principles :
the linguistic coverage must be
elementary but must include phenomena
that allow a rapid, concise and
s p o n t a n e o u s i n t e r a c t i o n , s u c h as
anapho~a (ellipsis, pronouns, etc.)
the linguistic competence and limits
of t h e i n t e r f a c e m u s t be e a s i l y a n d
r a p i d l y p e r c e i v e d by t h e u s e r .
t h e i n t e r f a c e m u s t be e q u i p p e d w i t h
s t r a t e g i e s a n d p r o c e d u r e s for l e a d i n g
t h e u s e r to a d j u s t h i s l i n g u i s t i c
c o m p e t e n c e to t h e c a p a c i t i e s of t h e
system.
a semantlc parser transforms the
syntactic analysis into
a semantic
representation by consulting the
knowledge base.
- an evaluator consults the knowledge
b a s e a n d p r o d u c e s a n s w e r s to q u e s t i o n s
given their semantic representation.
-
a general system guides the user and
h e l p s h i m to f o r m u l a t e a n d r e f o r m u l a t e
his queries.
T h e s y s t e m is e n t l r e l y p r o g r a m m e d in P R O L O G
II a n d r u n s on v a r i o u s c o m p u t e r s (VAX, S P S
and micro-computers).
Responses are given
instantaneously.
E e r e is a n e x a m p l e
INTERFACILE :
> comment
crder
of
a dialogue
un
flchler
?
u t i l l s e z la c o m m a n d e
CREATE
nomflchler
:
-
W e h a v e i l l u s t r a t e d t h e s e p r i n c i p l e s in an
application : a natural language (French)
i n t e r f a c e for a c q u i r i n g t h e f o r m a l c o m m a n d s
of s o m e o p e r a t i n g s y s t e m l a n g u a g e s . ( T h e
e x a m p l e s g i v e n h e r e c o n c e r n DCL of D i g i t a l
Equipment Corporation).
> comment
INTERFACILE's
The
system
of
son
contenu
- utilisez l'ddlteur
commande :
EDIT
nomfichler
:
- a portable syntactic grammar
w r i t t e n in t h e f o r m a l i s m of
M e t a m o r p h o s i s G r a m m a r s [2].
-
modifier
dependent
of
> comment copier
rdpertolre ?
[4].
a domain dependent knowledge base
w r i t t e n in a s u b s e t of p r e d i c a t e l o g i c
(Horn Clauses).
data
and
un
avec
fichier
la
a syntactic parser coupled with the
g r a m m a r a n d t h e l e x i c o n - g r a m m a r (i)
p r o d u c e s i n t e r m e d i a t e a n a l y s e s of
q u e s t i o n s , a n d (2) g e n e r a t e s s o m e
m e s s a g e s in c a s e of e r r o r s .
dane
un
u t l l l s e z la c o m m a n d e
COPY
nomflchier
[nomrdpertoire]
:
> c o m m e n t r e n o m m e r ce d e r n i e r ?
u t i l i s e z la c o m m a n d s :
RENAME/DIRECTORY
[ancienrdpertoire]
[nouveaurdpertoire]
-
<Dialogue
46
?
French
lexicon-grammar
O p e r a t i n g on t h e s e l i n g u i s t i c
domain knowledge :
-
:
ARCHITECTURE
is c o m p o s e d
- a domain
?
- u t i l i s e z la c o m m a n d e
PRINT
nom£ichier
> comment
2.
l'imprimer
with
I>
( T h e p r o m p t ">" p r e c e d e s t h e u s e r ' s q u e r i e s ,
t h e p r o m p t ..... p r e c e d e s I N T E R F A C I L E ' s
a n s w e r s . E n g l i s h t r a n s l a t i o n s of t h e
d i a l o g u e s a r e g i v e n in t h e a p p e n d i x ) .
3.
LINGUISTIC
COVERAGE
4.
INTERFACILE
handles
only elementary
s~ntactlc
structures°
In
order to ensure
a concise
and spontaneous
dialogue,
proforsLs have been introduced
such as :
'°
pronouns
(le,
I
)
eur
....
-possessives
la,
les,
(son,
demonstratlves
ce dernier~
sa,
en,
y,
(celui-ci,
)
ceux-ci,
.
.)
comment
copier
rSpe~tol~'e ?
un
flchier
dans
a
un
"- u t l l i s e z
la c o m m a n d s
:
COPY
nomfichier
[nomrQper'toire]
>
comment
•"
?
l ' e f f a c e r
'~1 ' ~'
renvoi e ~
tapez
le
:
fichier
?
(i
Pgpertoire
?
(2
d e vo'tre c h o i x .
num4ro
<Dialogue
2>
Proform
r ~ s o l t t t l o n is b a s e d s o l e l y
on
lexical
a~d syntactic
information.
This
strategy
Is v i t a l
in t h e f r a m e w o r k
of a
didact.ic system
oriented
towards
beginners
as t h e f o l l o w i n g
dialogue
shows
:
> comment
envoyer
utilisateur
?
utilisez
HAIL
> comment
"le"
%apez
>
le
un
la
message
commands
supprimer
renvoie
le
A un
:
?
&
:
message
?
(1)
utilisateur
?
(2)
num4ro
de votre
choix.
2
INTERFACILE
n'en
salt comment
:
sait
rien,
supprimer
supprimer
supprimer
un
un
un
<Dialogue
3>
Knowing
that error recovery
is a c o m p l e x
t a s k in t h e " r e s t r i c t e d "
framework
of
programming
languages
(limited
syntax
and
rJ. g o r o u s l y
defined
semantics),
one can
appreciate
-the d i f f i c u l t y
of e n d o w i n g
natural
language
interfaces
with such
capabilities.
One approach
t o "the p r o b l e m
of e r r o r
recoverJng
is t o " a c c e p t "
user queries
that
deviate
from the system's
expectations
and
(unbeknown
to t h e u s e r ) m a n i p u l a t e
them
into a form that can be analysed.
FoP an
overview
of t h i s a p p r o a c h ,
s e e [1]. T h i s
method
is c o s t l y
to i m p l e m e n t ,
and moreover
}%as 'two t h e o r e t i c a l
faults
:
(I) T h e r e
is n o g u a r a n t e e
that the
system's
interpretation
of a " d e v i a n t "
query will correspond
to t h e u s e r ' s
intention
in p o s i n g
the question.
(2) T h e r e w i l l a l w a y s
b e a l i m i t to t h e
degree
of d e v i a t i o n
the system
can tolerate
before
it g i v e s u p t r y i n g
to analyse
a user
query.
B u t if t h e t r a n s f o r m a t i o n
of d e v i a n t
queries
into recognizable
structures
is
performed
automatically,
the user will
*lever k n o w w h e r e t h i s l i m i t l l e s , a n d m a y
believe
that the system
c a n m a k e s e n s e of
anything
he enters.
The distinction
between
the sentences
the system
interprets
correctly
i~nd t h o s e w h i c h
it e n t i r e l y
rejects
will seem arbitrary
to him.
mais
envoyer
un message
6crire
un message
fichier
r6pertoive
message
If t h e p r o f o r m
resolution
had been based on
the domain
semantics,
the system
would have
produced
%he answer
for" s u p p r e s s i n g
a
m e s s a g e .
argue that the quality
of a n a t u r a l
language
interface
must be estimated
not
o n l y in t e r m s of i t s l i n g u i s t i c
coverage
b u t a l s o in t e r m s of t h e p r o c e d u r e s
for
dealing
with incorrect,
extragrammatical
(i.e. correct
but not expected
b~ the
interface)
or s e m a n t i c a l l y
deviant
sentences.
Ue
.
If a n a m b i g u i t y
is d e t e c t e d
during
the
r e s o l u i : i o n of a p r o f o v m ,
INTERFACILF, asks
question~
as i n t h e f o ] . ] o w i n g d i a l o g u e
:
>
REFORHULATION
Given the plethora
of s y n t a c t i c
structures
and the complexity
of m e n t a l
processes
involved
in n a t u r a l
language
understanding,
the linguistic
competence
of i n % e f f a c e s
yet
remains
limited.
If w e r e s o r t
to such
systems
to r e q u e s t
~ service
or obtain
information
that we lack, we generally
know
much more than the interface
itself
on the
various
w a y s for
fo~mulatlng
our query.
lui,
ses ....
QUERY
The strategy
developped
and implemented
in
INTERFACILE
is q u i t e d i f f e r e n t .
Our
philosophy
is n o t to m i s l e a d
the user
concerning
the system's
real capabilities,
but rather
to lead his linguistic
competence
to t h a t of t h e i n t e r f a c e .
H e r e is a n e x a m p l e
strategy
:
> comment
ajouter
d'un flchier
?
-
illustrating
A un
pour "ajouter",
construction
:
fichier
utilisez
such
is
a
contenu
la
47
ajouter
[quelque
[quelque
chose]
chose]
(ou t a p e z
/ pour
&
compl4tez
> comment
ajouter
is a n o t h e r
example
> comment envoyer
terminal ?
initlallssr
initialiser
4>
<Dialogue
:
un m e s s a g e
- pour "envoyer", utilisez
constructions
:
envoyer
annulet)
...
<Dialogue
Here
c r 4 e r un f i c h i e r
~dlter un fichler
effacer un fichler
dans
The guidance given here goes beyond
linguistic reformulation.
It c o n c e r n s t h e
s e m a n t i c s of t h e a p p l i c a t i o n d o m a i n . N o t e
t h a t t h e i n f o r m a t i o n g i v e n to t h e u s e r is
n o t p r e p r o g r a m m e d , but is (I) d e d u c e d f r o m
t h e k n o w l e d g e b a s e a n d (2) g e n e r a t e d b y t h e
linguistic component (grammar,
lexicon-grammar and parsers).
un
les
5.
envoyer
[quelque
[quelque
sur
> comment
7>
[quelque chose]
[quelqu'un]
&
compl4tez
un disque
une dlsquette
(ou t a p e z
envoyer
chose]
chose]
/ pour
annulet)
...
CONCLUSION
As far as t h e d o m a i n of a p p l i c a t i o n is
c o n c e r n e d , I N T E R F A C I L E h a s m u c h in c o m m o n
w i t h s y s t e m s l i k e UC [9] or I N T E R I X [5].
T h e o r i g i n a l i t y of o u r
effort we have devoted
<Dialogue
system
to :
lies
in t h e
5>
INTERFACILE explains exactly which part
t h e q u e s t i o n it d o e s n ' t u n d e r s t a n d : an
u n k n o w n w o r d , a v e r b w i t h an i n c o r r e c t
p r e p o s i t i o n or u n e x p e c t e d o r d e r of
c o m p l e m e n t s , etc. In c a s e o£ s p e l l i n g
errors,
s o l u t i o n s for c o r r e c t i o n a r e
g i v e n to t h e u s e r [8].
of
- l i n g u i s t i c p h e n o m e n a s u c h as a n a p h o r a
that ensure a natural dialogue.
s t r a t e g i e s a n d p r o c e d u r e s for
reformulation
in o r d e r to l i v e w i t h t h e
u n a v o i d a b l e l i n g u i s t i c l i m i t a t i o n s of
any interface.
To g u i d e t h e u s e r in r e f o r m u l a t i n g h i s
query, the grammar and the lexicon-grammar
a r e c o n s u l t e ~ as k n o w l e d g e b a s e s . T h e u s e r
may reformulate his query with the
information given by INTERFACILE.
(At a n y m o m e n t , t h e u s e r c a n a l s o o b t a i n
l i s t s of v e r b s , n o u n s , p r e p o s i t i o n s ,
pronouns, etc.).
the
O u r r e s e a r c h a n d e x p e r i e n c e in d e v e l o p i n g
a p p l i c a t i o n s in t h e s e t w o d o m a i n s h a v e led
us to b e l i e v e t h a t it is n o t p r a c t i c a l to
a d d p r o c e d u r e s to an a l b e a d y e x i s t i n g
s y s t e m to m a k e it u s e r - £ r l e n d l y . O n t h e
contrary, these problems must be taken into
a c c o u n t in t h e d e s i g n p h a s e , as w e h a v e d o n e
in d e s i g n i n g I N T E R F A C I L E .
6. A C K N O W L E D G E M E N T S
W h e n t h e u s e r h a s a n e r r o n e o u s or i n c o m p l e t e
v i e w of t h e a p p l i c a t i o n d o m a i n , I N T E R F A C I L E
p o i n t s out h i s m i s u n d e r s t a n d i n g ,
as in t h e
following dialogue :
> comment
version
imprimer
?
le
flchler de quoi
p l u t f t de :
fichier
fichier
version
fichler
?
INTERFACILE
example
> comment
We thank the Centre Nondial d'Informatique
(CNI, P a r i s ) for g i v i n g us t h e o p p o r t u n i t y
to d e v e l o p a v e r s i o n of I N T E R F A C I L E on a
V A X 785.
7. REFERENCES
[i] C a r b o n e l l J., H a y e s P., " R e c o v e r y
S t r a t e g i e s for P a r s i n g E x t r a g r a m m a t i c a l
L a n g u a g e " , A m e r i c a n J o u r n a l 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 , 9, 3-4, 1983.
6>
:
initialiser
INTERFACILE n'en
salt comment :
48
parle
(tout simplement)
d'un r~pertolre
d'un fichier
<Dialogue
Another
d'une
W e a r e gra'te£ul to H a n n a h B l a u for h e r
f r u i t f u l c o m m e n t s on a p r e l i m i n a r y v e r s i o n
of t h i s p a p e r .
un
fichier
salt
rien,
?
mais
[2] C o l m e r a u e r A., Les G r a m m a i r e s d e
N4tamorphoses,
GIA, L u m i n y , U n i v e r s i t 4
Alx-Narseille
If, 1975, a n d " M e t a m o r p h o s i s
G r a m m a r s " in N a t u r a l L a n g u a g e C o m m u n i c a t i o n
W i t h C o m p u t e r s , B o l c L. ed., S p D l n g e r V e r l a g
1978.
[3] D u c h i e r
D., S a b a t i e r
P., I N T E R F R A N C E :
Un
prototype
d'interface
en l a n g u e
franGalse,
Rapport
de recherche,
CGE, Harcoussis,
1982.
"it"
-
refers
enter
and the
P r o c . of
[4] G r o s s H . , " L e x l c o n - G r a m m a r s
syntactic
analysis
of F r e n c h " ,
COLING,
Karlsruhe,
1984.
Dialogue
3
> how
[5] G u e z S . , S a b b a g h
S., "INTERIX:
Un
systbme
d'aide
& l'utlllsation
d'Unix",
Confdrence
AFCET,
Paris,
1984.
[6] O l l v e l r a
E., P e r e l r a
L., S a b a t i e r
P.,
"ORBI: An expert system
for
environmental
resources
evaluation
through
natural
language,
P r o c . of F i r s t
International
Logic
Programming
Conference,
Marsellle,
1982.
> how
[7] P i q u e J . F . , S a b a t i e r
P., " A n i n f o r m a t i v e ,
adaptable
and efficient
natural
language
consultable
database
system",
P r o c . of E C A I
Conference,
1982.
>2
the
I send
use the
HAIL
can
-
[8] S a b a t l e r
P., A P r o l o g
spelling
correction,
Note
1985.
: Translation
Dialogue
i
command
"it"
refers
the
of
sample
I create
can
> how
a
file
command
filename
I print
I
it
modify
> how can I copy
directory
?
Dialogue
4
dialogues
can
> how
?
(I)
(2)
choice.
know,
but
he
:
a
can
5
> how
to
a
file
the
content
contents
by t h e
Copy
the
a
into
a
Dialogue
latter
can
6
I delete
can
[olddirectory]
[newdirectory]
into
a directory?
?
a message
in
use
the
[something]
[something]
to
on
(or
type
I send
cancel)
7
:
[somebody]
[something]
/ to
cancel)
I prin't
a
file
of
a version
?
INTERFACILE
?
"talks
a directory
of a f i l e
:
can
-
terminal?
structures
a file
a f i l e of
a version
Dialogue
a
...
file of what
about
:
:
file
it
/ to
:
?
use the command
:
COPY
filename
[directoryname]
can
type
...
"send",
complete
> how
file
I send
send
send
?
> how
I
I append
for
the command
:
filename
[dlrectoryname]
I rename
(or
:
can
:
:
can
-
message
user ?
of y o u r
?
?
its
- use
the
command
RENAME/DIRECTORY
> how
:
for "append"
use the structure
:
append
[something]
to [something]
> how
use
COPY
-
2
to
?
send a message
write
a message
suppress
a file
suppress
a directory
suppress
a message
Dialogue
- use the editor,
command :
EDIT
filename
Dialogue
?
:
use the command
PRINT
fllename
can
> how
it
INTERFACILE
doesn't
k n o w s h o w to :
> how
use the
CREATE
-
a
:
number
complete
> how
to
:
can
-
user
> how can I append
of a f i l e ?
APPENDIX
> how
a message
program
for
technique,
LADL,
R., " T a l k i n g
to
U N I X in E n g l i s h :
of U C " P r o c . of A A A I C o n f e r e n c e ,
[9] U i l e n s k y
An overview
1982.
(i)
(2)
choice.
I suppress
enter
-
:
:
can
-
to
file ?
directory
?
number
of y o u r
I initialize
a
file
?
INTERFACILE
doesn't
know, but he
knows how to :
create
a file
edit a file
delete
a file
initialize
a floppy disk
initialize
a disk
49