Postnikov square

In algebraic topology, a Postnikov square is a certain cohomology operation from a first cohomology group H¹ to a third cohomology group H³, introduced by Postnikov (1949). (Eilenberg 1952) described a generalization taking classes in H^t to H^2t+1.

References

• Eilenberg, Samuel (1952), "Homotopy groups and algebraic homology theories", Proceedings of the International Congress of Mathematicians, Cambridge, Massachusetts, 1950, vol. 2, Providence, R.I.: Amer. Math. Soc., pp. 350–353, http://mathunion.org/ICM/ICM1950.2/, retrieved 2011-04-08  PDF
• Hazewinkel, Michiel, ed. (2001), "Postnikov square", Encyclopedia of Mathematics, Springer Science+Business Media B.V. / Kluwer Academic Publishers, ISBN 978-1-55608-010-4, https://www.encyclopediaofmath.org/index.php?title=Main_Page 
• Postnikov, M. M. (1949), "The classification of continuous mappings of a three-dimensional polyhedron into a simply connected polyhedron of arbitrary dimension" (in Russian), Doklady Akademii Nauk SSSR, New Series 64: 461–462