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> I have always seen evolutionary algorithm as a version of gradient descent... which is extremely wasteful Evolutionary algorithms work by sampling a combinat

> I have always seen evolutionary algorithm as a version of gradient descent... which is extremely wasteful Evolutionary algorithms work by sampling a combinatorial solution space, and learning about the interactions between solution components. This is made explicit (and much more elegant) in the definition of EDAs: https://en.wikipedia.org/wiki/Estimation_of_distribution_algorithm https://en.wikipedia.org/wiki/Estimation_of_distribution_alg... By contrast, gradient descent makes the assumption that such interaction effects don't exist or don't matter, which doesn't work for most optimisation problems - you get stuck in local optima.

eru 9y ago
Of course you can mix your gradient descent with simulated annealing. But that gets close to evolutionary algorithms.
rdlecler1 9y ago
Evolutionary algorithms may also let you evolve the architecture. Think of a fly brain evolving into a human brain using the same genetic toolbox. With learning algorithms your assuming a fixed architecture. Hard to think how we’d get open ended evolutionary AI without evolutionary algorithms. At that point learning algorithms is the context dependent optimization step after neurogenesis.
- halflings 9y ago
  The terms you are using are too vague, and seem disconnected from the reality of these algorithms. How do evolutionary algorithms let you evolve the architecture? You define a model space, and explore it stochastically (with different evolutionary strategies). The model space you are exploring is linked to a specific architecture. Regardless, there's also efforts in Deep Learning to automatically learn optimal network architectures ("AutoML").
halflings 9y ago
Thanks! That link was really helpful. I guess some optimisation methods using a Hessian take those interaction effects into consideration, but they are too expensive and not used in practice. > doesn't work for most optimisation problems - you get stuck in local optima. This bit is not necessarily true. In practice, and given the high dimensionality, it is (apparently) quite hard to get stuck in local optima. [0] [0] https://www.quora.com/How-come-neural-networks-dont-get-stuck-in-poor-local-optima-Why-are-there-so-many-high-quality-local-optima https://www.quora.com/How-come-neural-networks-dont-get-stuc...
- randomsearch 9y ago
  > This bit is not necessarily true. In practice, and given the high dimensionality, it is (apparently) quite hard to get stuck in local optima. [0] In almost every optimisation problem I've encountered in practice, you do get stuck in local optima using simple techniques like SGD. Interaction effects are everywhere, and create local optima.

eru 9y ago

Of course you can mix your gradient descent with simulated annealing. But that gets close to evolutionary algorithms.

rdlecler1 9y ago

Evolutionary algorithms may also let you evolve the architecture. Think of a fly brain evolving into a human brain using the same genetic toolbox. With learning algorithms your assuming a fixed architecture. Hard to think how we’d get open ended evolutionary AI without evolutionary algorithms. At that point learning algorithms is the context dependent optimization step after neurogenesis.

halflings 9y ago
The terms you are using are too vague, and seem disconnected from the reality of these algorithms. How do evolutionary algorithms let you evolve the architecture? You define a model space, and explore it stochastically (with different evolutionary strategies). The model space you are exploring is linked to a specific architecture. Regardless, there's also efforts in Deep Learning to automatically learn optimal network architectures ("AutoML").

halflings 9y ago

Thanks! That link was really helpful. I guess some optimisation methods using a Hessian take those interaction effects into consideration, but they are too expensive and not used in practice. > doesn't work for most optimisation problems - you get stuck in local optima. This bit is not necessarily true. In practice, and given the high dimensionality, it is (apparently) quite hard to get stuck in local optima. [0] [0] https://www.quora.com/How-come-neural-networks-dont-get-stuck-in-poor-local-optima-Why-are-there-so-many-high-quality-local-optima https://www.quora.com/How-come-neural-networks-dont-get-stuc...

randomsearch 9y ago
> This bit is not necessarily true. In practice, and given the high dimensionality, it is (apparently) quite hard to get stuck in local optima. [0] In almost every optimisation problem I've encountered in practice, you do get stuck in local optima using simple techniques like SGD. Interaction effects are everywhere, and create local optima.