2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/161590In this paper I introduce modular symbols for Maass wave cusp forms. They appear in the guise of finitely additive functions on the Boolean algebra generated by intervals with non--positive rational ends, with values in analytic functions (pseudo--measures in the sense of [MaMar2]). After explaining the basic issues and analogies in the extended Introduction, I construct modular symbols in the sec. 1 and the related Lévy--Mellin transforms in the sec. 2. The whole paper is an extended footnote to the Lewis--Zagier fundamental study [LZ2].25 pages. Typos fixed, a dedication to F. Hirzebruch addedNumber TheoryAlgebraic Geometry11F37text