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Learning Invariances and Hierarchies . Pierre Baldi University of California, Irvine. Two Questions. “If we solve computer vision, we have pretty much solved AI.” A-NNs vs B-NNs and Deep Learning. If we solve computer vision…. If we solve computer vision….
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Learning Invariances and Hierarchies Pierre Baldi University of California, Irvine
Two Questions • “If we solve computer vision, we have pretty much solved AI.” • A-NNs vs B-NNs and Deep Learning.
If we solve computer vision… • If we solve computer audition,….
If we solve computer vision… • If we solve computer audition,…. • If we solve computer olfaction,…
If we solve computer vision… • If we solve computer audition,…. • If we solve computer olfaction,… • If we solve computer vision, how can we build computers that can prove Fermat’s last theorem?
Invariances • Invariances in audition. We can recognize a tune invariantly with respect to: intensity, speed, tonality, harmonization, instrumentation, style, background. • Invariances in olfaction. We can recognize an odor invariantly with respect to: concentrations, humidity, pressure, winds, mixtures, background.
Non-Invariances • Invariances evolution did not care about (although we are still evolving!...) • We cannot recognize faces upside down. • We cannot recognize tunes played in reverse. • We cannot recognize stereoisomers as such. Enantiomers smell differently.
Origin of Invariances • Weight sharing and translational invariance. • Can we quantify approximate weight sharing? • Can we use approximate weight sharing to improve performance? • Some of the invariance comes • from the architecture. • Some may come from the • learning rules.
Learning Invariances 1-11 111 E 11-1 symmetric connections wij=wji Hebb Acyclic orientation of the Hypercube O(H) Isometry I(O(H)) O(H) Hebb Hebb I(H) H Isometry
Deep Learning ≈ Deep Targets ? Training set: (xi,yi) or i=1, . . ., m
In spite of the vanishing gradient problem, (and the Newton problem) nothing seems to beat back-propagation. • Is backpropagation biologically plausible?
Mathematics of Dropout (Cheap Approximation to Training Full Ensemble)
Two Questions • “If we solve computer vision, we have pretty much solved AI.” • A-NNs vs B-NNs and Deep Learning.