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Whenever possible I prefer to express inputs in mathematical notation (rather than text commands) as I feel this helps one think like a mathematician, leaving the calculations to Mathematica "in the background." (Of course not all functions can be expressed in mathematical notation, such as Reduce or FullSimplify, and so on.)

Thus I use ESC for typesetting integrals and such, or use the Basic Math palette.

Consider this code:

Resolve[ForAll[x, a x^2 + a x - 4 < 0]]

(* $-16 < a \leq 0$ *)

The symbol $\forall$ in the Mathematica palette seems to be appropriate to replace ForAll, but doesn't work:

Resolve[\!\(
\*SubscriptBox[\(\[ForAll]\), \(x\)]\([a\ x^2\  + \ a\ x - 4 < 0]\)\)]

I've tried a number of variations, without success.

How can one express a function call, such as above, using the $\forall$ symbol?

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    $\begingroup$ \[ForAll] seems work. $\endgroup$
    – cvgmt
    Commented Aug 18, 2022 at 6:05
  • $\begingroup$ @cvgmt: That certainly typesets the symbol, but when I use that in the full input function call it sets the symbol but doesn't support the desired computation. (v. 11.3). What am I missing? $\endgroup$
    – David G. Stork
    Commented Aug 18, 2022 at 6:07
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    $\begingroup$ \[ForAll] then use Ctrl _ to put the lower x and then another expression. $\endgroup$
    – cvgmt
    Commented Aug 18, 2022 at 6:09
  • $\begingroup$ I apologize if I'm missing something basic, but can you typeset the \[ForAll] and actually get my sample code (involving Reduce and such) to work? Actually compute the desired answer? I can't! $\endgroup$
    – David G. Stork
    Commented Aug 18, 2022 at 6:12
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    $\begingroup$ Resolve[\!\( \*SubscriptBox[\(\[ForAll]\), \(x\)]\(a\ x^2\ + \ a\ x - 4 < 0\)\)] $\endgroup$
    – cvgmt
    Commented Aug 18, 2022 at 6:12

1 Answer 1

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An animation maybe useful for such input.

enter image description here

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  • $\begingroup$ Above and beyond the call of duty! Thanks! ($+1, \checkmark$). My personal preference is to use ESC... but no matter. $\endgroup$
    – David G. Stork
    Commented Aug 18, 2022 at 15:43

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