Mixtape Output Layer for Neural Networks

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Solution Overview

Problem

Conventional softmax output layers in neural networks are limited by their low-rank output representations, which are insufficient for modeling complex natural language or context-dependent vocabularies, and alternative solutions like Mixture of Softmaxes are computationally expensive, making them impractical for systems with limited computational budgets.

Innovation Solution

The Mixtape output layer employs a vector gating mechanism and sigmoid tree decomposition to generate high-rank output representations, reducing computational cost by avoiding expensive softmax operations and sharing gate values for infrequent outputs, allowing it to be integrated into existing neural networks as a replacement for conventional output layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a conventional softmax output layer is used, then computational cost is low, but output representation rank is limited to low-rank which is insufficient for modeling complex natural language

Engineering Contradiction:
Improveoutput representation rankVSAvoidcomputational efficiency
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The output layer is segmented into multiple independent softmax components, each handling a subset of the vocabulary. This segmentation allows the system to achieve high-rank output representations by combining multiple softmaxes while maintaining computational efficiency through parallel processing of independent components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single softmax operation to a mixture of multiple softmaxes, adding a dimensional aspect to the output space. This enables the model to capture complex dependencies in natural language by combining multiple probability distributions across different dimensions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If Mixture of Softmaxes is used to generate high-rank output representations, then expressiveness improves, but computational cost increases significantly in terms of memory and time

Engineering Contradiction:
Improveoutput representation rankVSAvoidcomputational cost
Core Design Contradiction:
Device complexityVSUse of energy by moving object

Solution Approach 1:

Different parts of the vocabulary are assigned different qualities of softmax components based on their frequency and importance. Frequent words are handled by more accurate softmaxes while less frequent words use simplified processing, optimizing the balance between representation quality and computational cost.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts parameters such as the number of softmax components and their dimensionalities based on the input data characteristics and computational budget. This allows the system to adapt the complexity of the output representation to the specific task requirements.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS11481609B2Computationally efficient expressive output layers for neural networks
Publication Date: 2022.10.25 GOOGLE LLC
  • US11481609B2 patent drawing
  • US11481609B2 patent drawing
  • US11481609B2 patent drawing

AI summary

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for incorporating a computationally efficient expressive output layer in a neural network. The output layer is configured to map a received hidden state to a probability distribution over a vocabulary of possible outputs by generating, from the hidden state, a respective context embedding for each of a plurality of gates; for each of the possible outputs in the vocabulary, computing a gated logit for the possible output by applying an output embedding for the possible output to the weighed sum; and generating the probability distribution over the vocabulary of possible outputs by applying a softmax to the gated logits for the possible outputs in the vocabulary.