tf.contrib.kfac.loss_functions.MultiBernoulliNegativeLogProbLoss

Class MultiBernoulliNegativeLogProbLoss

Neg log prob loss for multiple Bernoulli distributions param'd by logits.

Represents N independent Bernoulli distributions where N = len(logits). Its Fisher Information matrix is given by,

F = diag(p * (1-p)) p = sigmoid(logits)

As F is diagonal with positive entries, its factor B is,

B = diag(sqrt(p * (1-p)))

Properties

dist

The underlying tf.distributions.Distribution.

fisher_factor_inner_shape

The shape of the tensor returned by multiply_fisher_factor.

fisher_factor_inner_static_shape

Static version of fisher_factor_inner_shape.

hessian_factor_inner_shape

The shape of the tensor returned by multiply_hessian_factor.

hessian_factor_inner_static_shape

Static version of hessian_factor_inner_shape.

inputs

The inputs to the loss function (excluding the targets).

params

Parameters to the underlying distribution.

targets

The targets being predicted by the model.

Returns:

None or Tensor of appropriate shape for calling self._evaluate() on.

Methods

__init__

__init__(
logits,
targets=None,
seed=None
)


Initialize self. See help(type(self)) for accurate signature.

evaluate

evaluate()


Evaluate the loss function on the targets.

evaluate_on_sample

evaluate_on_sample(seed=None)


Evaluates the log probability on a random sample.

Args:

• seed: int or None. Random seed for this draw from the distribution.

Returns:

Log probability of sampled targets, summed across examples.

multiply_fisher

multiply_fisher(vector)


Right-multiply a vector by the Fisher.

Args:

• vector: The vector to multiply. Must be the same shape(s) as the 'inputs' property.

Returns:

The vector right-multiplied by the Fisher. Will be of the same shape(s) as the 'inputs' property.

multiply_fisher_factor

multiply_fisher_factor(vector)


Right-multiply a vector by a factor B of the Fisher.

Here the 'Fisher' is the Fisher information matrix (i.e. expected outer- product of gradients) with respect to the parameters of the underlying probability distribtion (whose log-prob defines the loss). Typically this will be block-diagonal across different cases in the batch, since the distribution is usually (but not always) conditionally iid across different cases.

Note that B can be any matrix satisfying B * B^T = F where F is the Fisher, but will agree with the one used in the other methods of this class.

Args:

• vector: The vector to multiply. Must be of the shape given by the 'fisher_factor_inner_shape' property.

Returns:

The vector right-multiplied by B. Will be of the same shape(s) as the 'inputs' property.

multiply_fisher_factor_replicated_one_hot

multiply_fisher_factor_replicated_one_hot(index)


Right-multiply a replicated-one-hot vector by a factor B of the Fisher.

Here the 'Fisher' is the Fisher information matrix (i.e. expected outer- product of gradients) with respect to the parameters of the underlying probability distribtion (whose log-prob defines the loss). Typically this will be block-diagonal across different cases in the batch, since the distribution is usually (but not always) conditionally iid across different cases.

A 'replicated-one-hot' vector means a tensor which, for each slice along the batch dimension (assumed to be dimension 0), is 1.0 in the entry corresponding to the given index and 0 elsewhere.

Note that B can be any matrix satisfying B * B^T = H where H is the Fisher, but will agree with the one used in the other methods of this class.

Args:

• index: A tuple representing in the index of the entry in each slice that is 1.0. Note that len(index) must be equal to the number of elements of the 'fisher_factor_inner_shape' tensor minus one.

Returns:

The vector right-multiplied by B. Will be of the same shape(s) as the 'inputs' property.

multiply_fisher_factor_transpose

multiply_fisher_factor_transpose(vector)


Right-multiply a vector by the transpose of a factor B of the Fisher.

Here the 'Fisher' is the Fisher information matrix (i.e. expected outer- product of gradients) with respect to the parameters of the underlying probability distribtion (whose log-prob defines the loss). Typically this will be block-diagonal across different cases in the batch, since the distribution is usually (but not always) conditionally iid across different cases.

Note that B can be any matrix satisfying B * B^T = F where F is the Fisher, but will agree with the one used in the other methods of this class.

Args:

• vector: The vector to multiply. Must be the same shape(s) as the 'inputs' property.

Returns:

The vector right-multiplied by B^T. Will be of the shape given by the 'fisher_factor_inner_shape' property.

multiply_hessian

multiply_hessian(vector)


Right-multiply a vector by the Hessian.

Here the 'Hessian' is the Hessian matrix (i.e. matrix of 2nd-derivatives) of the loss function with respect to its inputs.

Args:

• vector: The vector to multiply. Must be the same shape(s) as the 'inputs' property.

Returns:

The vector right-multiplied by the Hessian. Will be of the same shape(s) as the 'inputs' property.

multiply_hessian_factor

multiply_hessian_factor(vector)


Right-multiply a vector by a factor B of the Hessian.

Here the 'Hessian' is the Hessian matrix (i.e. matrix of 2nd-derivatives) of the loss function with respect to its inputs. Typically this will be block-diagonal across different cases in the batch, since the loss function is typically summed across cases.

Note that B can be any matrix satisfying B * B^T = H where H is the Hessian, but will agree with the one used in the other methods of this class.

Args:

• vector: The vector to multiply. Must be of the shape given by the 'hessian_factor_inner_shape' property.

Returns:

The vector right-multiplied by B. Will be of the same shape(s) as the 'inputs' property.

multiply_hessian_factor_replicated_one_hot

multiply_hessian_factor_replicated_one_hot(index)


Right-multiply a replicated-one-hot vector by a factor B of the Hessian.

Here the 'Hessian' is the Hessian matrix (i.e. matrix of 2nd-derivatives) of the loss function with respect to its inputs. Typically this will be block-diagonal across different cases in the batch, since the loss function is typically summed across cases.

A 'replicated-one-hot' vector means a tensor which, for each slice along the batch dimension (assumed to be dimension 0), is 1.0 in the entry corresponding to the given index and 0 elsewhere.

Note that B can be any matrix satisfying B * B^T = H where H is the Hessian, but will agree with the one used in the other methods of this class.

Args:

• index: A tuple representing in the index of the entry in each slice that is 1.0. Note that len(index) must be equal to the number of elements of the 'hessian_factor_inner_shape' tensor minus one.

Returns:

The vector right-multiplied by B^T. Will be of the same shape(s) as the 'inputs' property.

multiply_hessian_factor_transpose

multiply_hessian_factor_transpose(vector)


Right-multiply a vector by the transpose of a factor B of the Hessian.

Here the 'Hessian' is the Hessian matrix (i.e. matrix of 2nd-derivatives) of the loss function with respect to its inputs. Typically this will be block-diagonal across different cases in the batch, since the loss function is typically summed across cases.

Note that B can be any matrix satisfying B * B^T = H where H is the Hessian, but will agree with the one used in the other methods of this class.

Args:

• vector: The vector to multiply. Must be the same shape(s) as the 'inputs' property.

Returns:

The vector right-multiplied by B^T. Will be of the shape given by the 'hessian_factor_inner_shape' property.

sample

sample(seed)


Sample 'targets' from the underlying distribution.