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Encoder

As explained in Optimization Algorithms: AI techniques for design, planning, and control problems

An encoder is a neural-network component that transforms each element of an input sequence into a context-dependent hidden representation.

An encoder transforms each input element into a context-dependent hidden representation, making sequential or graph-structured information easier for later model components to use. section 11.3.3 section 11.3.1

An encoder typically performs these roles:

  • Processes an input sequence with a recurrent neural network, often using LSTM or GRU units. section 11.3.3
  • Produces one hidden state for each input element, with each state incorporating context from the sequence. section 11.3.3
  • Supplies representations to a decoder or attention mechanism that selects, generates, or classifies information. section 11.9
  • Maps graph nodes into low-dimensional vectors using node position, neighborhood structure, features, or combinations of these. section 11.3.1

Encoding points for a convex hull

In a pointer network, an encoder processes a sequence of two-dimensional points and creates hidden states that summarize each point in context. A decoder and pointer attention then assign probabilities to input positions, selecting the next convex-hull point. A small implementation trains on random point sets with PyTorch, Adam, negative log-likelihood loss, and validation accuracy; a predicted hull can be compared with SciPy’s hull. section 11.9

Figure 11.19 Solving the convex hull problem using Ptr-Net. The output in each step is a pointer to the input that maximizes the probability distribution.

Follow the pointer-network diagram to see encoded sequence representations feeding attention, which points to the next input element. section 11.9

Figure 11.4 Graph embedding

Use the graph-embedding figure to contrast node encoders, which map graph structure and features into a latent vector space. section 11.3.1

How Optimization Algorithms: AI techniques for design, planning, and control problems covers it

How deep it goes
Explains recurrent processing, hidden states, graph mappings, and training examples, but does not derive encoder equations in detail.
Examples
Uses convex-hull point sequences, pointer selection, graph node embeddings, Cora data, and graph convolutional networks.
What you can do after
Apply via PyTorch or PyTorch Geometric by training sequence or graph models that generate hidden or embedding representations.
How it connects
Connects encoders to recurrent neural networks, decoders, attention mechanisms, pointer networks, graph embedding, and latent spaces.

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This explainer was generated by Manning's knowledge graph from the text of Optimization Algorithms: AI techniques for design, planning, and control problems. The section links point to the parts of the book it draws on.