2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/96039We study the interaction of electrons with phonons in strongly correlated solids, having high-T_c cuprates in mind. Using sum-rules, we show that the apparent strength of this interaction strongly depends on the property studied. If the solid has a small fraction (doping) delta of charge carriers, the influence of the interaction on the phonon self-energy is reduced by a factor delta, while there is no corresponding reduction of the coupling seen in the electron self-energy. This supports the interpretation of recent photoemission experiments, assuming a strong coupling to phonons.4 pages, RevTeX, 2 eps figuresStrongly Correlated ElectronsMaterials Sciencetext