models/official/nlp/modeling/layers/README.md

Layers

Layers are the fundamental building blocks for NLP models. They can be used to assemble new layers, networks, or models.

• DenseEinsum implements a feedforward network using tf.einsum. This layer contains the einsum op, the associated weight, and the logic required to generate the einsum expression for the given initialization parameters.

• MultiHeadAttention implements an optionally masked attention between query, key, value tensors as described in "Attention Is All You Need". If from_tensor and to_tensor are the same, then this is self-attention.

• CachedAttention implements an attention layer with cache used for auto-agressive decoding.

• MultiChannelAttention implements an variant of multi-head attention which can be used to merge multiple streams for cross-attentions.

• TalkingHeadsAttention implements the talking heads attention, as decribed in "Talking-Heads Attention".

• Transformer implements an optionally masked transformer as described in "Attention Is All You Need".

• TransformerDecoderLayer TransformerDecoderLayer is made up of self multi-head attention, cross multi-head attention and feedforward network.

• ReZeroTransformer implements Transformer with ReZero described in "ReZero is All You Need: Fast Convergence at Large Depth".

• OnDeviceEmbedding implements efficient embedding lookups designed for TPU-based models.

• PositionalEmbedding creates a positional embedding as described in "BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding".

• SelfAttentionMask creates a 3D attention mask from a 2D tensor mask.

• MaskedSoftmax implements a softmax with an optional masking input. If no mask is provided to this layer, it performs a standard softmax; however, if a mask tensor is applied (which should be 1 in positions where the data should be allowed through, and 0 where the data should be masked), the output will have masked positions set to approximately zero.

• MaskedLM implements a masked language model. It assumes the embedding table variable is passed to it.

• ClassificationHead A pooling head over a sequence of embeddings, commonly used by classification tasks.

• GatedFeedforward implements the gated linear layer feedforward as described in "GLU Variants Improve Transformer".