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Glossary

An internal representation. It can be a random variable in a probabilistic model or a deterministic feature array. State which meaning is used.

One unit in a sequence. It may be a discrete ID or a continuous vector. A token is not necessarily one image patch.

A prior models a latent before observing an input. A posterior conditions on the observed input. A learned encoder may approximate the true posterior.

A finite table of vectors. Quantization chooses an entry, stores its index, and passes its vector to a decoder.

An operation that preserves a value in the forward pass but blocks derivatives through that path.

A model of conditional factors along an order. It does not require discrete values or a particular Transformer architecture.

Use observed earlier targets as context during training. Free-running generation instead uses earlier model predictions.

Reconstruction / generation · 重建 / 生成

Section titled “Reconstruction / generation · 重建 / 生成”

Reconstruction starts from an observed input and asks what survives encoding and decoding. Generation samples new content from a learned distribution, possibly with a condition.

Combine conditional and unconditional model predictions during sampling. Guidance strength changes output quality, diversity, and possibly computation.

FID applied to reconstructed or generated image sets. The evaluator and sample protocol matter; neither directly proves paired pixel accuracy or visual understanding.

A linear classifier trained on frozen features. An attentive pooling head is a different, nonlinear protocol.

APE supplies absolute position features. RoPE rotates query/key channel pairs according to coordinates, producing relative phase differences in attention.

A learned matrix changes vector width. It does not necessarily reduce information or sequence length.

Convert real scores to positive values that sum to one. Each output is exp(score) divided by the sum of exponentials.

For one observed class k, the loss is −log p(k). Assigning more probability to the correct class lowers the loss.

An expected log-density ratio between distributions. It is nonnegative and is generally asymmetric. Specify which distribution is first.

A lower bound on log marginal likelihood. A VAE maximizes expected reconstruction log-likelihood minus KL from its approximate posterior to its prior.

Normalize a feature vector using its mean and variance, then optionally apply learned scale and shift. This differs from dataset-level latent standardization.

Add a transformed branch to its input: y=x+F(x). A gate can control the branch contribution. This is unrelated to residual quantization.

A paired perceptual distance based on learned visual features. Its network and preprocessing are dependencies, not raw pixel arithmetic.

Train a discriminator to distinguish real from generated samples, while training a generator to produce samples that fool it. Loss variants differ.

Number of function evaluations used by a sampler. Specify which network is evaluated; one small MLP call and one full Transformer call have different costs.

An ODE specifies the time derivative of a state. Euler takes a step using the current derivative times a time interval. Finite steps generally introduce numerical error.

Quantize feature coordinates into signs/bits instead of searching an explicitly stored vector table. Training still needs a gradient estimator and distribution-related objectives.

Use a hard or discrete forward value but substitute a differentiable backward rule. It is a chosen estimator, not the exact derivative of the hard operation.

Represent a weight update as the product of two narrow matrices, ΔW=BA. Rank controls the size of this update family.

A matrix of inner products between feature channels or vectors. Matching it constrains correlations; it does not enforce exact pixel correspondence.

Save earlier keys and values so causal decoding need not recompute unchanged history. Bidirectional context updates can invalidate this assumption.

Divide a stated code payload by the number of image pixels. A nominal fixed-length count omits entropy coding, headers, model weights, and container overhead.

A scale that changes the sharpness of a probability distribution or contrastive score. Its meaning depends on the exact formula and sampling implementation.

Guidance / rejection · 引导 / 拒绝采样

Section titled “Guidance / rejection · 引导 / 拒绝采样”

Guidance changes sampling predictions. Rejection selects a subset of already generated candidates. Both can improve a score while changing diversity and cost.