XPost: sci.math   
   From: janburse@fastmail.fm   
      
   Hi,   
      
   A Prolog logical variable is not immutable,   
   it transitions all the time from uninstantiated   
   to instantiated, during unification.   
      
   Also the value the logical variable represents   
   is not immutable, since it might point to a   
   Prolog term which is non-ground, this   
      
   Prolog term might have other Prolog logical variables,   
   which do also such transitions, making the   
   while Prolog term transitioniong from less ground   
      
   to more ground, or even worse to a larger   
   term with even more Prolog logical variables,   
   and so on, leading to the phaenomenon of   
      
   perpetual processes or concurrent logic programming.   
   In particular the existence quantifier ∃ in logic   
   programming is not unique existence ∃!. For   
      
   example the following is true:   
      
   ∃x x = f(y)   
      
   But x has not a "single value", the existence   
   is more witness to of a kind of skolem function   
   dependency, namely that for each y, there   
      
   is some f(y). What they write is only useful   
   for a certained moded form of Prolog and unification,   
   where the equations have unique existence of   
      
   ground terms or some other value domain.   
      
   Bye   
      
   Mild Shock schrieb:   
   > Hi,   
   >   
   > Its their take of Logical variable, which   
   > might not be the same as a Prolog logical variable.   
   >   
   > ------------------ cut here ----------------   
   >   
   > 2.1 Logical variables and equations   
   > A program executes by solving its equations, using   
   > the process of unification. For example,   
   >   
   > ∃x y z. x = ; x= <2,z>; y   
   >   
   > is solved by unifying x with  and with <2, z>;   
   > that in turn unifies  with <2, z>, which unifies   
   > y with 2 and z with 3. Finally, 2 is returned as the   
   > result. Note carefully that, as in any declarative   
   > language, logical variables are not mutable; a logical   
   > variable stands for a single, immutable value.   
   >   
   > We use "∃" to bring a fresh logical variable into   
   > scope, because we really mean "there exists an x   
   > such that .... "   
   >   
   > ------------------ cut here ----------------   
   >   
   > Of course the above is utter nonsense, written   
   > from somebody who doesn't know what a Prolog logical   
   > variable is, shifting in the same sentence from   
   >   
   > the attribution of "immutable" of a variable, to   
   > the attribution of "immutable" of the value   
   > of a variable. This is quite hillarious.   
   >   
   > Bye   
   >   
   > Mild Shock schrieb:   
   >> Hi,   
   >>   
   >> Its from this paper:   
   >>   
   >> The Verse Calculus:a Core Calculus for Functional Logic Programming   
   >> SIMON PEYTON JONES, Epic Games, United Kingdom   
   >> GUY STEELE, Oracle Labs, USA   
   >> https://simon.peytonjones.org/assets/pdfs/verse-March23.pdf   
   >>   
   >> Don't blame me for what they write.   
   >> But mostlikely your eruption is just from   
   >> a clueless Nazi Retard, namely the paid   
   >>   
   >> troll you are, getting money from Putin.   
   >>   
   >> Bye   
   >>   
   >> Franz Sneijders schrieb:   
   >>> Mild Shock wrote:   
   >>>   
   >>>> We use “∃” to bring a fresh logical variable into scope, because we   
   >>>> really mean “there exists an x such that ···.”   
   >>>   
   >>> idiot, there is no any x over there. And it doesn't need to be a   
   >>> variable,   
   >>> a constant suffices.   
   >>>   
   >>   
   >   
      
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