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Today I have started reading stable homotopy. I have came across the notion of a pmap which is basically equivalence class of maps from cofinal sub-spectra. My query is what do we mean by degree of such map?

Tritte
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I'm sorry you got no response. By 'degree' they mean a shift in index in the underlying maps of spaces. So a 'map of spectra of degree $r$' is the data consisting of maps of CW complexes $E_n \to F_{n-r}$ satisfying certain properties. (I hope I got the signs right.) Equivalently, it's just a map of spectra $E \to \Sigma^{-r} F$.