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Connections: apply synapsesCompetition() in adaptSegment() #584

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Connections: apply synapsesCompetition() in adaptSegment() #584

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@breznak breznak commented Jul 24, 2019 •
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  • SP uses synapse pruning, same as TM has been doing
    • make pruning default to true in adaptSegment (unless it breaks too many tests)?
      • or altogether remove the param and just use it?
    • this brings a performance gain about 5%
  • WIP Connections.adaptSegment calls newly added synapsesCompetition
    • results in more synapses being pruned -> which turns to another 5-10% speedup
    • better synaptic activations (fewer extremes) as described in the original PR
    • find way to set reasonable default paramaters
  • tests expected to fail with mismatches

Follow up to #466
Fixes #558

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Connections:destroySynapse fixup, use find
7394e27 
instead of lower_bound, caused err in Debug.
Seems faster
@breznak
SP: allow synapse pruning in adaptSegment
37a0d98 
already used in TM
makes SP 10% faster! (on MNIST 55->50s)
@breznak
Connections:adaptSegment use synapsesCompetition
fd58f25 
normally in learning.
@breznak
Connections: introduce Random rng_ member
9a1bbf9 
and use it for synapsesCompetition()
@breznak
Revert "Connections: introduce Random rng_ member"
b2cc6c4 
This reverts commit 9a1bbf9.
@breznak breznak added SP optimization code code enhancement, optimization, cleanup..programmer stuff labels Jul 24, 2019
@breznak breznak self-assigned this Jul 24, 2019
@breznak breznak closed this Jul 24, 2019
@breznak breznak reopened this Jul 24, 2019
@breznak breznak closed this Jul 24, 2019
@breznak breznak reopened this Jul 24, 2019
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breznak commented Jul 24, 2019
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src/htm/algorithms/Connections.cpp Outdated
@@ -479,6 +475,9 @@ void Connections::adaptSegment(const Segment segment,
}
}

//balance synapses using competition on dendrite
synapseCompetition(segment, 4, 10); //FIXME derive these numbers
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calling synapseCompetition from adaptSegment

  • this works pretty well, with synapse pruning many synapses get removed which leads to a considerable speedup
  • set the min/max parameters somehow smarter
    • I guess those should ideally be around stimulusThreshold ?
    • the tighter the boundary, the more syns get removed, the faster SP (on MNIST) is.
      • but where is the line? What is the disadvantage? I'd think too tight boundary is more prone to noice?

CC @ctrl-z-9000-times

src/htm/algorithms/Connections.hpp
@@ -510,7 +510,7 @@ class Connections : public Serializable
*/
void synapseCompetition( const Segment segment,
const SynapseIdx minimumSynapses,
const SynapseIdx maximumSynapses);
const SynapseIdx maximumSynapses);
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TODO

  • this should have some parametric default values
  • replace (or provide overload) with percentages off the range [stimulusThreshold, maxSynapsesPerSegment]?

src/htm/algorithms/SpatialPooler.cpp
@@ -702,7 +702,7 @@ Real SpatialPooler::avgConnectedSpanForColumnND_(UInt column) const {
void SpatialPooler::adaptSynapses_(const SDR &input,
const SDR &active) {
for(const auto &column : active.getSparse()) {
connections_.adaptSegment(column, input, synPermActiveInc_, synPermInactiveDec_);
connections_.adaptSegment(column, input, synPermActiveInc_, synPermInactiveDec_, true);
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SP also does prune synapses (like TM)

  • default to true/or even rm the parameter, when all use true now

@breznak breznak mentioned this pull request Jul 24, 2019
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@breznak breznak added the high label Aug 1, 2019
@breznak breznak mentioned this pull request Aug 1, 2019
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breznak commented Aug 1, 2019

This PR now gains importance with a problem I've discovered for NAB detector usingour HTM: htm-community/NAB#15 (comment)

For this PR to be considered complete, we need to resolve "how do we choose the lower/upper bound for syn competition". Currently it is hardcoded. #584 (review)
Unless a better solution is found, I like the proposal: #584 (comment)
to provide percentages off the range [stimThreshold, maxSynapsesPerSegment], which would look like [stimThresh*(1.0 + lowerPct), maxSperSeg*(1.0 - upperPct)].

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breznak commented Jun 4, 2020
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Aiming to finish this PR soon..

src/htm/algorithms/Connections.cpp
@@ -519,6 +519,9 @@ void Connections::adaptSegment(const Segment segment,
}
}

//balance synapses using competition on dendrite
synapseCompetition(segment, 8, 11); //FIXME derive these numbers
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this is the only big remaining issue - how to choose good values for these?
Any tips @ctrl-z-9000-times ?

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SP, TM use synapseCompetition()
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