#925 featurep of subscripted variables

open
nobody
7
2006-08-26
2006-05-14
Barton Willis
No

(%i1) featurep(a,real);
(%o1) false <-- OK

(%i2) featurep(a[1],real);
(%o2) true <-- not OK

Do we have a policy? Are all mapatoms except %i and
infinity real? That would make %o1 wrong and %o2 correct.
Should the setting of domain make a difference?

Barton

Discussion

  • Robert Dodier
    Robert Dodier
    2006-05-17

    • labels: --> Lisp Core - Assume
     
  • Robert Dodier
    Robert Dodier
    2006-08-26

    • priority: 5 --> 7
     
  • Robert Dodier
    Robert Dodier
    2006-08-26

    Logged In: YES
    user_id=501686

    featurep is a pretty confused function. A substantial bit of
    logic has accreted onto featurep, but as it stands it is
    incomplete (as in the example above).

    We probably need to separate (1) the stuff which is just
    checking for declaration flags from (2) the stuff which is
    attempting to infer elementp(x, S) for S = reals, complexes,
    etc. I think featurep should implement (1), but not (2),
    which should be a revision of elementp.

    Bumping up the priority -- weakness of assume/declare stuff
    is a serious hindrance.