Russ,
Ok. So, the question is, what is the "value added" of saying "green state" rather than just saying that the "light is green". Something comes through the gate with the camel, so to speak. What is it? N From: Friam [mailto:[email protected]] On Behalf Of Russ Abbott Sent: Saturday, April 13, 2013 10:03 PM To: The Friday Morning Applied Complexity Coffee Group Subject: Re: [FRIAM] Systems, State, Recursion, Iteration. Never beaten over the head with "hypothetical construct" or "intervening variable". My notion of state is basic theoretical computer science. How an automaton (a formally defined mechanism such as a Turing Machine, Finite Automaton, etc.) reacts to its input depends on its state. This isn't intended to be particularly sophisticated. It's just a technique used when specifying how things interact with their environments. When a traffic light that controls a crosswalk is in the green state (in your direction) and you press the cross button, it ignores that input. When it's in its red state (in your direction) and you press the cross button, it starts counting down to turning green. How long the countdown will be depends on another element of its state: how much time has passed since the most recent green. -- Russ Abbott _____________________________________________ Professor, Computer Science California State University, Los Angeles My paper on how the Fed can fix the economy: ssrn.com/abstract=1977688 Google voice: 747-999-5105 Google+: plus.google.com/114865618166480775623/ vita: <http://sites.google.com/site/russabbott/> sites.google.com/site/russabbott/ CS Wiki <http://cs.calstatela.edu/wiki/> and the courses I teach _____________________________________________ On Sat, Apr 13, 2013 at 8:48 PM, Nicholas Thompson <[email protected]> wrote: Thanks, Steve. Will ponder all of this. Nick From: Friam [mailto:[email protected]] On Behalf Of Steve Smith Sent: Saturday, April 13, 2013 8:47 PM To: The Friday Morning Applied Complexity Coffee Group Subject: [FRIAM] Systems, State, Recursion, Iteration. Nick - It would be difficult to explain this (Marcus' definition of iteration vs recursion) to you without teaching you several key computer science concepts which are not necessarily difficult but are very *specific*. The first step would be to answer your question of days ago about what a "System" is. Physicists define System the same way Biologists (or even Social Scientists) do, just using different components and processes. It involves the relationship between the "thing" itself (a subset of the universe) and a model that represents it. Therein lies two lossy compressions: 1) Reductionism is at best a convenient approximation... no subset or subsystem is completely isolated (unless perhaps somehow what is inside a black hole is isolated from what is outside, but that might be an uninteresting, degenerate case?); 2) The model is not the thing... we've been all over this, right? Another lossy compression/projection of reality. oh and a *third*; 3) We can only measure these quantities to some degree of precision. In a system, a simultaneous measure every quantity of every aspect of the system is it's "state". In practice, we can only measure some of the quantities to some precision of some of the aspects, and in fact, that is pretty much what modeling is about... choosing that subset according to various limited qualities such as what we *can* measure and with what level of precision and with a goal in mind of answering specific questions with said model. At this point, we are confronted with "what means State?" Your preference for "Analytical Output" vs "State" I think reflects your attempt to think in terms of the implementation of a model (in a computer program, or human executed logic/algorithm). The problems with "Analytical Output" in this context arise from both "Analytical" and "Output". "Analytical" implies that the only or main value of the "state" is to do analysis on it. In Marcus example, it's main use is to feed it right back into an iterated model... no human may ever look at this "state". "Output" suggests (also) that the state is visible *outside* the system. While (for analytical purposes) we might choose to capture a snapshot of the state, it is not an "output", it is just the STATE of the system (see above). Marcus point was that in a recursive *program* (roughly a deterministic implementation rooted in formal symbol processing, of a model of some "system"), the "system" is nominally subdivided into physical or logical subsets or "subsystems" and executed *recursively* (to wit, by subdividing again until an answer can be obtained without further subdivision). In an iterative *program*, the entire (sub) system model is executed with initial conditions (state) one time, then the resulting state of that iteration is used as the initial conditions for the *next* iteration until some convergence criteria (the state of the system ceases to change above some epsilon) is met. I hope this helps... and doesn't muddy the water yet more? - Steve I don't know, I don't speak Haskell. --Doug On Sat, Apr 13, 2013 at 3:29 PM, Nicholas Thompson <[email protected]> wrote: Could be! Ok. Now that that is behind us, what did the message mean? N From: Friam [mailto:[email protected]] On Behalf Of Douglas Roberts Sent: Saturday, April 13, 2013 3:02 PM To: The Friday Morning Applied Complexity Coffee Group Subject: Re: [FRIAM] Tautologies and other forms of circular reasoning. Nick, I surprised that you are not more conversant in computer languages. You're always, well, niggling about the meaning of this word, or that one in the context of this or that conversation. With computer languages, there are very few ambiguities, contextual or other wise. Kind of like mathematics. For one as worried as you often appear to be about the true meaning of the written word, I would have thought that you would positively revel at the ability to express yourself with nearly absolute crystal clarity, no ambiguities whatsoever. Could it be that you seek out the ambiguities that are ever present in human languages to give yourself something to pounce upon and worry over, and to provide the opportunity to engage in nearly endless conversations? --Doug On Sat, Apr 13, 2013 at 2:05 PM, Nicholas Thompson <[email protected]> wrote: Can anybody translate this for a non programmer person? N -----Original Message----- From: Friam [mailto:[email protected]] On Behalf Of Marcus G. Daniels Sent: Saturday, April 13, 2013 1:10 PM To: [email protected] Subject: Re: [FRIAM] Tautologies and other forms of circular reasoning. On 4/12/13 5:40 PM, glen wrote: > Iteration is most aligned with stateful repetition. Recursion is most > aligned with stateless repetition. Purely functional constructs can capture iteration, though. $ cat foo.hs import Control.Monad.State import Control.Monad.Loops inc :: State Int Bool inc = do i <- get put (i + 1) return (i < 10) main = do putStrLn (show (runState (whileM inc get) 5)) $ ghc --make foo.hs $ ./foo ([6,7,8,9,10],11) ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com -- Doug Roberts [email protected] <http://parrot-farm.net/Second-Cousins> http://parrot-farm.net/Second-Cousins 505-455-7333 - Office 505-672-8213 - Mobile ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com -- Doug Roberts [email protected] <http://parrot-farm.net/Second-Cousins> http://parrot-farm.net/Second-Cousins 505-455-7333 - Office 505-672-8213 - Mobile ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com
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