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A Hopfield net
always makes decisions that reduce the
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energy.
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This
makes it impossible to escape from local minima.
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We can use
random noise to escape from poor minima.
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Start
with a lot of noise so its easy to cross energy
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barriers.
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Slowly
reduce the noise
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so
that the system ends up
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in
a deep minimum. This is
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“simulated
annealing”.
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We will come
back to simulated annealing later. For now,
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we will keep the
noise level fixed to avoid unneccessary
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complications in
explaining the other good things that
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result from
using stochastic units.
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