# Improved GAN

Posted by c cm on June 30, 2017

# Convergent GAN

## 1. feature matching ~= maximum mean discrepancy

Feature matching addresses the instability of GANs by specifying a new objective for the generator that prevents it from overtraining on the current discriminator.

p.2: we train the generator to match the expected value of the features on an intermediate layer of the discriminator.

 p.2: Letting f (x) denote activations on an intermediate layer of the discriminator, our new objective for the generator is defined as: Ex∼pdata f(x) − Ez∼pz(z)f(G(z)) 2. The discriminator, and hence f(x)

## 2. mini batch features ~= batch normalization

p.3: One of the main failure modes for GAN is for the generator to collapse to a parameter setting where it always emits the same point.

p.3: The concept of minibatch discrimination is quite general: any discriminator model that looks at multiple examples in combination, rather than in isolation, could potentially help avoid collapse of the generator.

one example:

## 3. historical averaging

 p.3: When applying this technique, we modify each player’s cost to include a term θ − 1 t θ[i] 2, t i=1where θ[i] is the value of the parameters at past time i.

fictitious play

0/1->0/0.9

## 5. virtual batch normalization

p.4: normalized based on the statistics collected on a reference batch of examples that are chosen once and fixed at the start of training