2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/229953The separability in parallel Gaussian interference channels (PGICs) is studied in this paper. We generalize the separability results in one-sided PGICs (OPGICs) by Sung \emph{et al.} to two-sided PGICs (TPGICs). Specifically, for strong and mixed TPGICs, we show necessary and sufficient conditions for the separability. For this, we show diagonal covariance matrices are sum-rate optimal for strong and mixed TPGICs.5 pages, 1 figure, to appear in proc. IEEE ISIT, June 2009Information Theorytext