Work
Thanks to Lefschetz and others, the cup product structure of cohomology was understood by the early 1940s. Steenrod was able to define operations from one cohomology group to another (the so-called Steenrod squares) that generalized the cup product. The additional structure made cohomology a finer invariant. The Steenrod cohomology operations form a (non-commutative) algebra under composition, known as the Steenrod algebra.
His book The Topology of Fibre Bundles is a standard reference. In collaboration with Samuel Eilenberg, he was a founder of the axiomatic approach to homology theory. See Eilenberg–Steenrod axioms.
Read more about this topic: Norman Steenrod
Famous quotes containing the word work:
“Not rarely, and this is especially true of wives and mothers, the motive behind assuming a disproportionate share of work and responsibility is completely unselfish. We want to protect, to spare those of whom we are fond. We forget that, regardless of the motive, the results of such action are almost always destructive and unproductive.”
—Hortense Odlum (1892–?)
“We have not the motive to prepare ourselves for a “life-work” of teaching, of social work—we know that we would lay it down with hallelujah in the height of our success, to make a home for the right man. And all the time in the background of our consciousness rings the warning that perhaps the right man will never come. A great love is given to very few. Perhaps this make-shift time filler of a job is our life work after all.”
—Ruth Benedict (1887–1948)
“What is the reason that women servants ... have much lower wages than men servants ... when in fact our female house servants work much harder than the male?”
—Samuel Johnson (1709–1784)