Table 1 Summary of notations used in the proposed method.

From: Multi-view affinity-based projection alignment for unsupervised domain adaptation via locality preserving optimization

Symbol

Description

\(x_i^s, y_i^s\)

Source sample and its one-hot label

\(x^t\)

Target domain sample input

\(r_{\theta }(x)\)

Predicted class probabilities from student network

\(r_{\theta }(x)_j\)

Response (confidence) for class j

\(\mathscr {U}\)

Relational matrix encoding inter-class similarity

\(f_i^s, g_i^s\)

Feature representations of source sample \(x_i^s\)

\(f_j^t, g_j^t\)

Feature representations of target sample \(x_j^t\)

\(d_{\epsilon }\)

Domain discriminator with parameters \(\epsilon\)

\(f \oplus g\)

Concatenated features for domain discrimination

\(\lambda _{da}, \lambda _{adv}\)

Weights for domain alignment and adversarial loss

\(\varphi , \theta\)

Parameters of teacher and student networks

X

Concatenated feature matrix from source and target domains

\(X_S\), \(X_T\)

Source and target domain feature matrices

\(x_i\)

A single feature vector from X

\(\mu\)

Mean vector of X

\(P_{\text {pca}}\)

PCA projection matrix

\(X_{\text {reduced}}\)

Dimensionality-reduced features after PCA

\(\tilde{x}_i\)

L2-normalized feature vector

\(W_{\text {all}}\)

Affinity matrix combining label and feature similarity

\(\alpha\)

Weighting coefficient for label similarity

\(\sigma\)

Gaussian kernel bandwidth parameter

L

Graph Laplacian matrix

D

Diagonal degree matrix of \(W_{\text {all}}\)

P

Projection matrix learned via LPP

\(\tilde{X}^s_{\text {proj}}, \tilde{X}^t_{\text {proj}}\)

Projected and normalized source and target features

\(\mu _S, \mu _T\)

Source class mean and target cluster mean in projected space

\(\tau _T(i)\)

Confidence score for target sample i

\(\theta _{c(i)}\)

Class-specific pseudo-label confidence threshold

p

Dynamic selection ratio decreasing over iterations

\(\text {prob}(i)\)

Max predicted class probability for sample i

\(\text {pseudoLabels}_T(i)\)

Refined pseudo-label for sample i

\(\textbf{P}_v\)

Predicted probability matrix from view v

\(\alpha _v\)

Weight for view v in fusion

\(D_v\)

Distance-based score for view v

\(\gamma _v\)

Bandwidth parameter for view weight computation

\(\textbf{P}_{\text {fused}}\)

Fused probability matrix from all views

\(\hat{y}_T(i)\)

Final predicted label for target sample i