Donna Y [email protected]
> On Sep 4, 2019, at 2:37 PM, Raul Miller <[email protected]> wrote: > > On Wed, Sep 4, 2019 at 2:19 PM Donna Y <[email protected]> wrote: >> Evaluated weak-form EMF entails the effect of historic data—something not >> available for a transaction that might be available in the future. > > But that information would be available in the future when the future > becomes the present. According to Maymin, that might be in 20 tears—that means his suggested method of proving P=NP couldn’t work for another 20 years. Why not propose a different Turing Machine and a Language it accepts—there are infinitely many. The Church-Turing thesis states that any sufficiently powerful computational model which captures the notion of algorithm is computationally equivalent to the Turing machine. > > That said, for practical reasons (even ignoring regulations) it's not > possible to extract all meaning from historical data. This is > especially true in high monetary velocity contexts. There isn't enough > time to perform more than superficial calculations. Maymin invokes the term Bounded Rationality (coined by Herbert A. Simon. In Models of Man) that says rational decisions are often not feasible in practice because of the intractability of the decision problem and the finite computational resources available for making them. No one is omniscient. EMH doesn't say that an efficient market price system would make us so. "All meaning" isn't the sort of information Fama was claiming fair prices transmit. Changes in stock prices convey relevant information about the supply and demand and expected return on company shares in a way that allows people to choose to buy, hold or sell those stocks as if they did consciously calculate and understand factors that affected changes in value, even if they don’t. A central planner needs to know about the changed value of firms in order to distribute resources appropriately, whereas individual agents in a free market are automatically encouraged to distribute their investments to shares with improved value without having to consciously grasp why prices change. > >> Market regulation aim to make the market competitive and fair as >> well as efficient. What they may want to eliminate if a loophole >> that would allow one or more participants to drain money from other >> participants unfairly and also undermine the primary purpose of the >> market which is to raise capital for firms. > > Market regulations attempt to do so. > > But regulations also have limits -- including jurisdictional limits. > This leads to fraud related issues (which, are -- practically speaking > -- another example of market inefficiency). Yes there is fraud or the possibility of fraud—does that make the market inefficient by definition. Fine, see below, it says nothing about SAT-1 or the class NP. > >> Even if market regulations eliminate market efficiency it is definitely >> false that >> market regulations eliminate NP-Completeness > > How [specifically] would this be false? In computational modeling the outputs of a computing system C are used to describe some behaviour of another system S under some conditions. The explanation for S’s behaviour has to do with S’s properties, not with a computation performed by the model. If Maymin is correct that EMH is equivalent to a specific N-complete problem C and if he solves the NP-complete problem then that proves C is in P—it has an efficient solution. By Maymin’s proposed proof that would imply EMH was efficient. If he could prove C has no efficient solution then by his logic the market is not efficient. Proving C, an NP-Complete problem, has an efficient solution proves P=NP. Else showing the market has regulators that make it inefficient then so be it, EMH is not efficient by definition. That does not prove anything about C or the class NP. > >> Economics is not mathematics—it is a social science attempting to explain >> social phenomena and distribution of resources among people. > > Sure, but economics uses mathematics, and if the math being used is > mathematically inconsistent, that means that any value in its results > didn't come from the math. Yes I said that. CS and Economics use math. In computational explanation some behaviour of a system S is explained by a particular kind of process internal to S—a computation—and by the properties of that computation. The mathematical description A that specifies the evolution of S only represents what is known about the evolution of S. Some factors that influence S’s evolution might be unknown, To include everything that is known about S in A may make the mathematics analytically or computationally intractable. > > Thanks, > > -- > Raul > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
