BPFK Section: lerfu Shifts
Well, when you put it that way... . There have been, however, quite a few occasions in the 43 years I taught logic (off and on) when spelling things out literally was important. How, for example, does one learn that your second sentence means your first on unless one finds out what the symbols mean, which requires symbol and meaning brought together somewhere (I rarely used a book). How, as the Polish logicians asked (this is not my experience, obviously), do you do logic in the dark for fear the Nazis would break in on you (one reason for Polish notation is that it is easier aurally than infix, lacking all those confusing parentheses)? It is not a major point (nothing about literals is a major point, since we rarely use them as such), but it does need a solution nonetheless. We don't only express formulae, we also describe them. (And {nibli} and its compounds are still the wrong words here for material implication. Invert A is also a moderately lousy version of the universal
quantifier sign, especially if combined with invert E for particular.)
pc
Rob Speer <rspeer@MIT.EDU> wrote:On Fri, Jan 30, 2004 at 12:08:52PM -0800, Jorge Llamb?as wrote:
> But I'd rather use the implication arrow itself for an implication arrow,
> and something like {lo nibli sinxa} to talk about them.
I'd like to draw more attention to this useful comment.
While the rest of the thread goes off with Stupid Zai Tricks, I want to
step back and ask: why in holy heck would you want to say an
_implication arrow_ out loud?
If you're expressing some logical statement, you don't say the arrow,
you say "implies" or "nibli". The arrow is a shorthand.
Compare the following two mathematical statements, and observe which one
would actually be spoken.
"For all x and all y, x equals y implies y equals x."
"Upside down capital A, x, upside down capital A, y, x, equals sign, y,
double arrow pointing to the right, y, equals sign, x."
--
mu'o mi'e rab.spir