20.08.2015 Views

process

K-theory and Noncommutative Geometry.pdf

K-theory and Noncommutative Geometry.pdf

SHOW MORE
SHOW LESS
  • No tags were found...

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

340 U. Bunke, T. Schick, M. Spitzweck, and A. ThomdiagramQ ET n jB !EExt 2 Sh Ab S=B .T n jB I T jB /DDExt 2 Sh Ab S=B .D.T jB /; D.E// D.E/!D.T n jB / Ext2Sh Ab S=B .D.T jB /I D.T n jB //aOcŠ Ext 2 Sh Ab S=B .Z jB ; Zn jB /ŠH 2 .BI Z n jB /.By construction the class a.P / 2 Ext 2 Sh Ab S=B .Z jB ; Zn jB/ classifies the Picard stackD.E/. This implies that Oc.P/ classifies the gerbe R ! B, i.e. Oc.P/ D c. yE/.6.4.7 It remains to construct the last entryuW H ˝EB yE y H op ! BT jEB yE(70)of the triple ‰.t/ D ..E; H /; . yE; yH/;u/, where we use Picture 6.1.11. Note thatH 1 .P / Š T jB . Construction 2.5.12 gives rise to a sequence of morphisms of PicardstacksBT jB ! P ! xP(we could write xP D E).We have an evaluation ev W P B D.P / ! BT jB . For a pair .r; s/ 2 Z Z weconsider the following diagram with two-cartesian squares.H r zB H y evsP D.P / BT jBu r;sHzry ˝Er ByR sH sP ˝ xP D.P / D.P /wE r B R s xP D.P /¹r; sº jBZ jB Z jB .

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!