ScalingStacks

0N87

Remark 9. The fact that RA,โˆ’R_{A,-} is a pseudonatural equivalence can be expressed equivalently as follows: for any object Xโˆˆ๐’žX\in\mathcal{C}, there exists an equivalence RA,X:AโŠ—Xโ†’XโŠ—AR_{A,X}\colon A\otimes X\to X\otimes A, and for any morphism f:Xโ†’Yf\colon X\to Y in ๐’ž\mathcal{C}, there exists a 2-isomorphism RA,f:(AโŠ—f)โˆ˜RA,Yโ‡’RA,Xโˆ˜(fโŠ—A)R_{A,f}\colon(A\otimes f)\circ R_{A,Y}\Rightarrow R_{A,X}\circ(f\otimes A):

AโŠ—X{\lx@inpgf@ignorespaces A\otimes X}XโŠ—A{\lx@inpgf@ignorespaces X\otimes A}AโŠ—Y{\lx@inpgf@ignorespaces A\otimes Y}YโŠ—A{\lx@inpgf@ignorespaces Y\otimes A}RA,X\scriptstyle{\lx@inpgf@ignorespaces R_{A,X}}AโŠ—f\scriptstyle{\lx@inpgf@ignorespaces A\otimes f}โ‡‘RA,f{\lx@inpgf@ignorespaces\Uparrow R_{A,f}}fโŠ—A\scriptstyle{\lx@inpgf@ignorespaces f\otimes A}RA,Y\scriptstyle{\lx@inpgf@ignorespaces R_{A,Y}}

such that (โˆ™โŠ—โ†’โ†’)(\bullet\otimes{\to}\to) and (โˆ™โŠ—โ‡“)(\bullet\otimes{\Downarrow}) commute.

Similarly, the fact that R~(A|โˆ’,โˆ’)\>\tilde{R}_{(A|-,-)} is a modification means that the diagrams (โˆ™โŠ—(โ†’โŠ—โˆ™))(\bullet\otimes({\to}\otimes\bullet)) and (โˆ™โŠ—(โˆ™โŠ—โ†’))(\bullet\otimes(\bullet\otimes{\to})) commute.

Original mathematics by the credited authors. Source collection and HTML conversion remain in progress.

John C. Baez, Martin Neuchl

Original source: arXiv:q-alg/9511013v2