On 29 Feb 2012, at 15:47, Alberto G.Corona wrote:

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On 29 feb, 11:20, Bruno Marchal <marc...@ulb.ac.be> wrote:On 29 Feb 2012, at 02:20, Alberto G.Corona wrote (to Stephen):A thing that I often ask myself concerning MMH is the questionaboutwhat is mathematical and what is not?. The set of real numbers is a mathematical structure, but also the set of real numbers plus the point (1,1) in the plane is.Sure. Now, with comp, that mathematical structure is more easily handled in the "mind" of the universal machine. For the ontology we can use arithmetic, on which everyone agree. It is absolutely undecidable that there is more than that (with the comp assumption). So for the math, comp invite to assume only what is called "the sharable part of intuitionist and classical mathematics.I do not thing in computations in terms of "minds of universal machines" in the abstract sense but in terms of the needs of computability of living beings.

I am not sure I understand what you mean by that. What is your goal?

`The goal by default here is to build, or isolate (by reasoning from`

`ideas that we can share) a theory of everything (a toe).`

`And by toe, most of us means a theory unifying the known forces,`

`without eliminating the person and consciousness.`

`The list advocates that 'everything' is simpler than 'something'. But`

`this leads to a measure problem.`

`It happens that the comp hypothesis gives crucial constraints on that`

`measure problem.`

The set of randomly chosen numbers { 1,43,4,.34, 3} is because it can be described with the samedescriptivelanguage of math. But the first of these structures have propertiesand the others do not. The first can be infinite but can bedescribedwith a single equation while the last must be describedextensively. . At least some random universes (the finite ones)can bedescribed extensively, with the tools of mathematics but they don´t count in the intuitive sense as mathematical.Why? If they can be finitely described, then I don't see why they would be non mathematical.It is not mathematical in the intuitive sense that the list of the ponits of ramdomly folded paper is not. That intuitive sense , more restrictive is what I use here.

Ah? OK.

What is usually considered genuinely mathematical is anystructure,that can be described briefly.Not at all. In classical math any particular real number ismathematically real, even if it cannot be described briefly.Chaitin'sOmega cannot be described briefly, even if we can defined it briefly.a real number in the sense I said above is not mathematical. in the sense I said above. In fact there is no mathematical theory about paticular real numbers. the set of all the real numbers , in the contrary, is.

`OK. Even for Peano Arithmetic, in fact. Basically, because a`

`dovetailer on the reals is an arithmetical object.`

`It looks like you define math by the "separable part of math" on which`

`everybody agree. Me too, as far as ontology is concerned. But I can't`

`prevent the finite numbers to see infinities everywhere!`

Also it must have good properties , operations, symmetries or isomorphisms with other structures so the structure can be navigated and related with other structures and the knowledge can be reused. These structures have a low kolmogorov complexity, so they can be "navigated" with low computing resources.But they are a tiny part of bigger mathematical structures. That'swhywe use big mathematical universe, like the model of ZF, or Category theory.If maths is all that can be described finitelly, then of course you are right. but I´m intuitively sure that the ones that are interesting can be defined briefly, using an evolutuionary sense of what is interesting.

I agree with you. The little numbers are the real stars :)

`But the fact is that quickly, *some* rather little numbers have`

`behaviors which we can't explain without referring to big numbers or`

`even infinities. A diophantine polynomial of degree 4, with 54`

`variables, perhaps less, is already Turing universal. There are`

`programs which does not halt, but you will need quite elaborate`

`transfinite mathematics to prove it is the case.`

So the demand of computation in each living being forces to admit that universes too random or too simple, wiith no lineal or discontinuous macroscopic laws have no complex spatio-temporalvolutes (that may be the aspect of life as looked from outside ofourfour-dimensional universe). The macroscopic laws are themacroscopiceffects of the underlying mathematical structures with which our universe is isomorphic (or identical).We need both, if only to make precise that very reasoning. Even incomp, despite such kind of math is better seen as epistemologicalthanontological.There is a hole in the transition from certain mathematical properties in macroscopic laws to simple mathematical theories of everything .

`Sure. especially that if we start from the observations, all theories`

`are infinite extrapolation from finite sample of data.`

The fact that strange, but relatively simple mathematical structure (M theory)

If you call that simple, even relatively ...

include islands of macroscopic laws that are warm for life.

`With comp, such picture is false. If we take it seriously, it leeds to`

`a reductionism so strong that it eliminates consciousness and persons.`

`It is contrary to the fact, if you agree that you are conscious <here-`

`and-now>.`

`With the computationalist hypotheses, based on an invariance principle`

`for consciousness, (yes doctor), we see that we have to justify the M-`

`theory, or whatever describing correctly the physical reality, from a`

`theory of consciousness (itself justifiable by the machine, for its`

`justifiable part).`

I do not know the necessity of this greed for reduction. The macroscopic laws can reigh in a hubble sphere, sustained by a gigant at the top of a turtle swimming in an ocean.

`It is an open, but soluble problem. If this is correct (which I doubt)`

`then the hubble sphere sphere sustained by a gigant at the top of a`

`turtle swimming in an ocean (of what?) has to be derived from logic,`

`numbers, addition and multiplication only.`

That's the point.

And our very notion of what is intuitively considered mathematical:"something general simple and powerful enough" has thehallmark ofscarcity of computation resources. (And absence of contradictionsfitsin the notion of simplicity, because exception to rules have to be memorized and dealt with extensively, one by one)Perhaps not only is that way but even may be that the absence of contradictions ( the main rule of simplicity) or -in computationa terms- the rule of low kolmogorov complexity _creates_ itself the mathematics.Precisely not. Kolmogorov complexity is to shallow, and lacks the needed redundancy, depth, etc. to allow reasonable solution to the comp measure problem.I can not gasp from your terse definitions what the comp measure problem is .

`Do you understand the notion of first person indeterminacy? Have you`

`read:`

http://iridia.ulb.ac.be/~marchal/publications/SANE2004MARCHALAbstract.html

`It is a deductive reduction of the mind-body problem into a body`

`problem in arithmetic. It gives the shape of the conceptual solution,`

`and toe.`

`Comp has the advantage of having already its science, computer`

`science, which makes it possible to translate a problem of philosophy-`

`theology in precise technical terms.`

`The shape of the conceptual solution can be shown closer to Plato's`

`theology, than Aristotle's theology, used by 5/5 atheists, 4/5 of the`

`Abrahamic religion, 1/5 by the mystics, and large part of some eastern`

`religion.`

What i know is that, kolmogorov complexity is critical for life. if living beings compute inputs to create appropriate outputs for survival. And they do it.

`Yes, it can have many application, but it is very rough, and computer`

`science provides many more notion of complexity, and of reducibility.`

`Brent cited a paper by Calude showing specifically this, notably.`

`Kolmogorov complexity might be the key of the measure problem, but few`

`people have succeeded of using it to progress. It might play some role`

`in the selection of some particular dovetailer, but it can't work, by`

`being non computable, and depending on constant. I don't know. I'm`

`afraid that the possible role for Kolmogorov complexity will have to`

`be derived, not assumed. or you might find an alternative formulation`

`of comp.`

That is, for example, may be that the boolean logic for example, is what it is not because it is consistent simpleand it´s beatiful, but because it is the shortest logic in terms of the lenght of the description of its operations, and this is the reason because we perceive it as simple and beatiful and consistent.It is not the shortest logic. It has the simplest semantics, at the propositional level. Combinators logic is far simpler conceptually, but have even more complex semantically.I meant the sortest binary logic.

`Classical logic is not the shorter binary logic. In term of the length`

`of its possible formal descriptions.`

I mean that any structure with contradictions has longer description than the one without them.,

?

`None logic get contradictions, with the notable exception of the`

`paraconsistant logics.`

`Intuitionist logic is a consistent (free of contradiction) weakening`

`of classical logic. Quantum logic too.`

`Note also that the term logic is vague. Strictly speaking I don't need`

`logic at the ontological level. I put it here for reason of simplicity.`

so the first is harder to discover and harder to deal with.,.

`You preach a choir. Classical logic is the one with the simplest`

`semantics. It is the common jewel of both Plato and Aristotle, and`

`with comp, it forces to distinguish proof from truth. Which I think is`

`the essence of science and religion (not of human academies and`

`churches, alas).`

`It looks we agree on some things: the importance of classical logic.`

`The need to restrict ourselves to the separable part of math.`

`Now, if you are interested in the mind-body problem, you might`

`understand, with some work, that the comp hypothesis reduces the`

`problem into a body problem, which takes the form of a relative`

`measure problem on computations. It shows that the physical laws have`

`an arithmetical origin, or a theoretical computer science origin.`

`I don't pretend that comp is true, just that it leads to that kind of`

`reversal for the global toe. It can be considered as strongly`

`reductionist ontologically, but it can be shown to prevent any`

`normative or complete theory for the persons and any other universal`

`numbers.`

`There might also be a flaw in the argument. Don't worry at all if you`

`find one. UDA1-7 is "easy".`

`The step 8 is too much concise in sane04, and you can find here a more`

`detailed explanation:`

http://old.nabble.com/MGA-1-td20566948.html

`The list was already discussing the "measure problem" related`

`naturally with the everything-type of theories. Comp adds a lot,`

`notably by making important the distinction between first person and`

`third person view, which is the key for the mind-body problem.`

`The second part (of sane04) is technical and thus more difficult`

`without the study of Mendelson, Boolos, or Davis 65 (the original`

`paper of Gödel, Church, Kleene, Post, Rosser). But you don't need that`

`to understand the comp mind-body problem, and the comp "reversal".`

`Information and complexity are important concepts, but there are many`

`other one, and in fine, it depends on what we are interested to solve`

`or clarify.`

Bruno

But the main problem of the MHH is that nobody can define what it is, and it is a priori too big to have a notion of first personindeterminacy. Comp put *much* order into this, and needs no moremaththan arithmetic, or elementary mathematical computer science at the ontological level. tegmark seems unaware of the whole foundation-of- math progress made by the logicians. Bruno.Dear Albert,One brief comment. In your Google paper you wrote, among other interesting things, "But life and natural selection demands a mathematical universe<https://docs.google.com/Doc?docid=0AW-x2MmiuA32ZGQ1cm03cXFfMTk4YzR4cn...somehow".Could it be that this is just another implication of the MMHidea? Ifthe physical implementation of computation acts as a selective pressure on the multiverse, then it makes sense that we would find ourselves in a universe that is representable in terms of Boolean algebras with their nice and well behaved laws of bivalence (a or not-A), etc.Very interesting ideas.Onward!Stephen

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