Re: [External] : Re: How to make M-x TAB not work on (interactive) declaration?

[Eduardo Ochs]

On Mon, 16 Jan 2023 at 15:56, Jean Louis <bugs@gnu.support> wrote:
>
> * Andreas Eder <a_eder_muc@web.de> [2023-01-16 20:42]:
> > > Maybe you know some reference to Lisp beginning why is it so?
> >
> > See http://www.lispworks.com/documentation/HyperSpec/Body/f_pl.htm for
> > #'+ and http://www.lispworks.com/documentation/HyperSpec/Body/f_st.htm
> > for #'*.
>
> Thanks.
>
> "Returns the product of numbers, performing any necessary type
> conversions in the process. If no numbers are supplied, 1 is
> returned."
>
> I understand 1 is returned, yet I am still searching for purpose.
>
> For now vague purpose is only to satisfy some other functions which
> process lists, like `reduce' or `apply', I am searching for
> confirmation if that was the sole purpose.

Hi Jean,

a few months ago I had to prepare some figures to explain to my
students what should be the "neutral elements" for some operations...
The main idea is that we want all these expressions to yield the same
result, including the two last ones, that are weird,

  (+ (+ 2 2) (+ 2 2 2 2 2))
  (+ (+ 2 2 2) (+ 2 2 2 2))
  (+ (+ 2 2 2 2) (+ 2 2 2))
  (+ (+ 2 2 2 2 2) (+ 2 2))
  (+ (+ 2 2 2 2 2 2) (+ 2))
  (+ (+ 2 2 2 2 2 2 2) (+))

and the same thing for these expressions:

  (* (* 2 2) (* 2 2 2 2 2))
  (* (* 2 2 2) (* 2 2 2 2))
  (* (* 2 2 2 2) (* 2 2 2))
  (* (* 2 2 2 2 2) (* 2 2))
  (* (* 2 2 2 2 2 2) (* 2))
  (* (* 2 2 2 2 2 2 2) (*))

My figures are in the pages 86 and 87 of this PDF,

  http://angg.twu.net/LATEX/2022-2-C2-tudo.pdf#page=86

and my real objective was to convince them that we had very good
reasons to decide that the result of (or) should be false the result
of (and) should be true, and then extend these ideas to "for all" and
"exists".

  Cheers,
    Eduardo