On 11 Jan 2014, at 00:54, meekerdb wrote:

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On 1/10/2014 1:42 AM, Bruno Marchal wrote:Second, a reality can exist without being computed. the best andsimple example is arithmetic. Only a very tiny part of it iscomputable (this is provable if you accept the Church Turing thesis).But it's questionable whether it "exists".

In which sense?

`Note that in the arithmetical expression: "ExAyEzAt P(x, y, z, t)",`

`the "E" has the same meaning than in the constructive sigma_1 ExP(x).`

`Existence in math is never necessarily computable in the usual`

`classical math, unless we work in non classical intuitionist logic`

`(but this recovered by the existence in the quantified S4Grz).`

`Keep in mind that "exists" has 8 different meaning in the eight`

`different hypostases, and you should say precisely if you talk of`

`psychological existence, physical existence, arithmetical existence ...`

Bruno

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