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We express the signature modulo 4 of a closed, oriented,
4k–dimensional PL manifold as a linear combination of
its Euler characteristic and the new absolute torsion invariant
defined by Korzeniewski [Absolute Whitehead torsion, Geom. Topol. 11 (2007)
215--249]. Let F→E→B be a PL fibre bundle, where F, E
and B are closed, connected, and compatibly oriented PL manifolds. We
give a formula for the absolute torsion of the total space E in terms
of the absolute torsion of the base and fibre, and then combine these
two results to prove that the signature of E is congruent modulo 4 to
the product of the signatures of F and B.
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