Hi Christian, What you describe is done in lines 58-60:
58. else if predictiveState(c, i, t) == 0 and predictiveState(c, i, t-1)==1 then 59. adaptSegments (segmentUpdateList(c,i), false) 60. segmentUpdateList(c, i).delete() If the cell was predictive at t-1 but is no longer predictive (and we know that it's not active either, because otherwise it would be a learning cell since it was previously predictive), then adaptSegments() is called with positiveReinforcement set to false, causing the synapses that were active (that made the cell predictive at t-1) to be decremented. -Mike _____________ Michael Ferrier Department of Cognitive, Linguistic and Psychological Sciences, Brown University [email protected] On Wed, Jan 29, 2014 at 9:10 PM, Christian Cleber Masdeval Braz < [email protected]> wrote: > > Hi > > I was studying the TP algorithm and didn't understand one point. > > In the beginning, permanence values are assigned aleatory to distal > dendrites segments of all cells (as in the initialization of the SP). > > In time t, the region predicts a bunch of cells based on the activation > of their segments. A segment is active if it have a minimum number of > active synapses connected with active cells in time t. In time t + 1, the > cells that were predicted and are in active columns (and just that in > active columns) will have their synapses permanence values updated > according. > > But, what about the false positives, the cells that were predicted > ocasionaly just because they had an active segment that fit well with input > in time t, but they never occur. Don't they will be predicted again and > again when the input in time t occur? I couldn't see where the algorithm > treat this issue. > > In the last part, it does > > for c, i in cells > 55. if learnState(c, i, t) == 1 then => > update just the cells that are in an active column > 56. adaptSegments (segmentUpdateList(c, i), true) > 57. segmentUpdateList(c, i).delete() > > Doesn't necessary to decrement the permanence value of those connected > synapses in the distal dentrite segments of cells that don't occur? > > > Christian > > > > > > > > > > > _______________________________________________ > nupic mailing list > [email protected] > http://lists.numenta.org/mailman/listinfo/nupic_lists.numenta.org > >
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