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Latent space

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

A latent space is a lower-dimensional representation space whose vectors encode information about observed data or structures.

A latent space is a lower-dimensional continuous space whose vectors compress information while preserving useful structure. For graphs, an encoder maps nodes into vectors using position, neighborhood structure, features, or a combination of these. section 11.3.1

Graph embeddings organize latent vectors according to graph relationships:

  • Place connected or nearby nodes close together, and separate disconnected or distant nodes. section 11.3.1
  • Use an encoder alone, or jointly optimize an encoder and decoder to preserve specified graph information. section 11.3.1
  • Distinguish transductive methods, which represent only training nodes, from inductive methods, which generalize to unseen nodes or graphs. section 11.3.1

Node embeddings with a graph convolutional network

A practical pipeline loads the Cora dataset with PyTorch Geometric, applies two GCNConv layers with ReLU and dropout, trains with Adam for 200 epochs, and evaluates the model.

Figure 11.4 Graph embedding

Visualizes the mapping from graph space into a low-dimensional embedding or latent space. section 11.3.1

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

How deep it goes
Explains the encoding objective, encoder-decoder variant, and transductive-inductive distinction, then demonstrates GCN training.
Examples
Demonstrates node embeddings with a two-layer GCN trained on the Cora dataset using PyTorch Geometric.
What you can do after
Builds node embeddings by implementing and training a GCN with PyTorch Geometric.
How it connects
Connects graph embedding with graph convolutional networks, encoder-decoder architectures, transductive learning, and inductive learning.

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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.