Path: utzoo!attcan!uunet!zephyr.ens.tek.com!uw-beaver!mit-eddie!snorkelwacker!usc!ucsd!pacbell.com!decwrl!shelby!eos!ptolemy!mehra From: mehra@ptolemy.arc.nasa.gov (Pankaj Mehra) Newsgroups: comp.ai.neural-nets Subject: Re: NN solution of non-deterministic problems. Doable or stupid? Message-ID: <6910@ptolemy.arc.nasa.gov> Date: 1 Aug 90 17:04:52 GMT References: <14121@shlump.nac.dec.com> Sender: usenet@ptolemy.arc.nasa.gov Organization: NASA-Ames Research Center, Moffett Field, CA Lines: 36 In article spoffojj@hq.af.mil (Jason Spofford) writes: >If you plotted the monthly rain accumulation amounts over the last 40 >years for Duluth, you would end up with a simple graph of rain fall >amounts over time. This graph would have a line that went up and down >depending on the seasons. What you are asking the NN to do is to >project what is going to happen in the future, based on what happened >in the past. > > I have not trained NN's (in the traditional approaches) so I >am a little unclear on exactly how to train the NN to perform this >function. David Rogers from RIACS in Mountain View, CA recently presented some results about characterizing rainfall in N. Australia using Kanerva's SDM. The problem he addressed looked more like a regression problem than a prediction problem. But he reported some good results on a very large problem. If I remember correctly, his approach resembles genetic search. The original query was: > Message-ID: <14121@shlump.nac.dec.com> > I'd like to know if it's possible to use neural nets to solve problems > that aren't fully deterministic, that is, similar inputs produce two or > more different outputs in different training cases. Look at Ivakhnenko and Lapa's book on Forecasting and Predicition Techniques. [I don't have the complete reference here.] Sometimes, you can model the determinsitic part and the stochastic parts separately. At other times, you might want to start from random intial behavior and bias it towards determinsitic behavior. You will most definitely need stochastic units in the network(s) you use. Pankaj Mehra University of Illinois