Re: assertion to English conversion?

>>>>> Joshua N Pritikin <Joshua> writes:

> On Mon, Oct 20, 2003 at 12:45:52PM -0700, Hans Chalupsky wrote:
>> There is no standard PowerLoom mechanism yet to do this.  The `lexeme'
>> and `phrase' assertions in pl-kernel-kb.ste are only some initial
>> steps towards a capability like this.  NL-rendering is fairly easy for
>> most ground assertions such as `(father-of frank joe)' (you could
>> easily write this yourself if you really need it).

> Hrm, that would probably be sufficient for my purposes.
> I just want something which is potentially as expressive
> as KM (U-Texas Knowledge Machine).

> Is there a way to compute the substitutions in the
> phrase relation?  If not, can you sketch how I can
> code this?

You'd have to use PLI function calls as shown below to perform the
proper string substitutions in the phrase string.  Here it goes -
first we generate the necessary KB definitions:

|= (in-module "PL-USER")

|= (clear-module "PL-USER")

|= (defrelation father-of (?child ?father)
     ;; Here I deviated from using the variable syntax for `phrase' and
     ;; instead used positional arguments which it easier to code this:
     :phrase "#2 is the father of #1"
     ;; I used a single valued relation instead of defining this
     ;; as a function, since looking up function proposition objects
     ;; via PLI is a bit tricky - send me mail (off list) if you need to:
     :single-valued true)

|r|FATHER-OF

;; this works around yet another deficiency of PLI which will go away
;; hopefully soon - without this call (or running a standard query first)
;; the assertions in the above definition won't be expanded - this
;; happens on demand but PLI functions don't yet trigger it automatically:
|= (process-definitions)

|= stop

Bye.

()
;; Now we run Lisp code that given a proposition object looks up its
;; relation and the relation's phrase and substitutes the arguments;
;; this should also give you an idea of how to write this in Java or
;; C++ if that's what you prefer:

CL-USER(65): (let* ((module (pli:get-module "PL-USER" stella::null))
                    (environment stella::null)
                    (prop
                     ;; generate a proposition object from a string:
                     (pli:get-nth-value
                      (pli:consify
                       (pli:s-conceive "(FATHER-OF JOE BILL)"
                                       "PL-USER"
                                       environment))
                      0))
                    ;; access the predicate object:
                    (predicate (pli:get-predicate prop))
                    ;; access the phrase string of the predicate:
                    (result
                     (pli:get-nth-string
                      (pli:get-nth-value
                       (pli:consify
                        (pli:get-binary-propositions
                         (pli:get-object "PHRASE" module environment)
                         predicate
                         stella::null module environment))
                       0)
                      2)))
               ;; substitute the arguments (this could additionally look
               ;; for `lexeme' values and substitute those:
               (loop for i from 1 to 2
                   do (setq result
                        (stella::replace-substrings
                         result
                         (pli:object-to-string (pli:get-nth-value prop i))
                         (format nil "#~d" i))))
               result)
"BILL is the father of JOE"  ;; ta da
CL-USER(66): 


So, this is a bit more than the sketch you asked for.  The reason why
this isn't built in yet is that we still need to decide on better
names for `phrase' or `lexeme' (most of our time we spend thinking
about names :-), whether they should also take a language argument,
and various other details.  Unfortunately, it's always a lot easier to
hack something up than to provide a nice, clean and general API to it.

Hans

--------------------------------------------------------------------------
PowerLoom home page:                 http://www.isi.edu/isd/LOOM/PowerLoom
PowerLoom forum:                                   [email protected]
PowerLoom request line:                      [email protected]
STELLA home page:                       http://www.isi.edu/isd/LOOM/Stella
--------------------------------------------------------------------------