2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/64984Topological 4-dimensional surgery is conjectured to fail, in general, for free fundamental groups. M. Freedman and P. Teichner have shown that surgery problems with an arbitrary fundamental group have a solution, provided they satisfy a certain condition on Dwyer's filtration on second homology. We give a new geometric proof of this result, and analyze its relation to the canonical surgery problems.minor changes; to appear in Math. Res. LettGeometric Topologytext