Laurent Bitjoka — Papers on Cortexa

arxiveess.SP2026-07-15

Tight Wavelet Frames on Graphs via Isometric Group Embedding

Spectral graph wavelets apply a kernel to the graph Laplacian spectrum. On an irregular graph their analyzing functions inherit a non-canonical eigenbasis, they do not form a tight frame, and reconstruction requires inverting a frame operator. We take a different route, built on…

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arxiveess.SP2026-07-14

Harmonic Analysis on Graphs via Isometric Group Embedding: A Canonical Fourier Transform, Shift, and Convolution for Network Signals

Rigobert Fokam Souop, Laurent Bitjoka

Graph signal processing built on the eigenvectors of a Laplacian or adjacency shift inherits three structural compromises: the eigenbasis is fixed only up to rotation within degenerate eigenspaces, the shift is not an isometry, and there is no genuine translation under which filt…

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