2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/149503We propose to measure valence-quark shadowing by observing charged pion productions in electron-nucleus scattering at HERA. Studies of shadowing phenomena in the valence-quark distribution could be useful in discriminating among various models, which produce similar results in the $F_2$ shadowing.3 pages, LATEX, fig. 1. Complete postscript file including the figure is available at ftp://ftp.cc.saga-u.ac.jp/pub/paper/riko/quantum1/saga-he-94.ps.gz or at http://www.cc.saga-u.ac.jp/saga-u/riko/physics/quantum1/kumano.html Email: kumanos@cc.saga-u.ac.jpNuclear TheoryHigh Energy Physics - Phenomenologytext