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|    Message 1,330 of 1,954    |
|    Ted Dunning to jones...@emporia.edu    |
|    Re: With vector utility is one less like    |
|    18 Mar 07 11:19:26    |
      From: ted.dunning@gmail.com              On Mar 15, 3:37 am, jones...@emporia.edu wrote:       > In conventional capitalist economics one assumes value       > monism and a scalar utility              I really don't think that the convenience of having a scalar objective       function is philosophically related to capitalism. The reason for       optimizing a scalar-valued objective is that it is a much simpler       problem to state. Real numbers form a total order which lets the       definition of "optimum" make sense.              If the parameters are real valued then you also get things like       gradients and Hessians to work with.              > It may be, however, that value monism is wrong and we       > can not reduce all rewards to a single scalar              As you note, this idea is hardly new.              But you should observe that most approaches to multiple objective       optimization start with some way of defining an order function on R^n,       if only so that you can say what "optimum" means. In many approaches,       this is done by defining some heuristic way of reducing the multiple       cost functions to a single value.              > Initial results suggest that use of a vector utility       > may make the system less likely of get stuck in local       > maxima. If the system can not improve L, for example,       > it may be able to increase N. After evolving for a while       > one may then find L and N can both improve.              This statement is way too over-arching.              First, there are many methods that avoid the problem of local minima       using scalar objectives. These include simulated annealing various       evolutionary algorithms. There are also a number of methods in many       settings that avoid the need for optimization, per se. For instance,       maximum likelihood methods are often better replaced by sampling       techniques which evaluate posterior likelihoods directly. Thus,       scalar objective functions with local minima are not a hopeless       problem.              Secondly, it has been known for some time that the introduction of       auxiliary variables can make many problems much easier. Latent       variable techniques are an impressive example of exactly this. For       instance, in regression problems where you are trying to estimate a       few parameters, it can be helpful to introduce two latent variables       per observed data point. Thus, this idea that increasing the       dimensionality of the problem is useful is hardly novel.              Most importantly, though, all of this has nothing to do with       capitalism or alternatives.              But you may also have something interesting.              Can you say more about your specific examples and methods?              [ comp.ai is moderated ... your article may take a while to appear. ]              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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