A cautionary paper appeared on the arXiv last week

Forsyth, I., B. Mesland, and A. Rennie. *Dense Domains, Symmetric Operators and Spectral Triples*. ArXiv e-print, June 6, 2013. http://arxiv.org/abs/1306.1580.

The paper is about the definition of *unbounded Fredholm modules* and how certain, initially plausible, weakenings of the definition do not work as expected. (Some well-known authors are called out for insufficient attention to these points; I was initially worried that *Analytic K-Homology* appears in the bibliography, but I don’t think Nigel and I are among the criminals here.)