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Homotopy Theory Seminar -- Hood Chatham

Homotopy Theory Seminar
December 5, 2019
11:30AM - 12:30PM
MW 154

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Add to Calendar 2019-12-05 11:30:00 2019-12-05 12:30:00 Homotopy Theory Seminar -- Hood Chatham Speaker: Hood Chatham (MIT)   Title: An Orientation Map for Higher Real E-theory   Seminar URL: https://www.asc.ohio-state.edu/fontes.17/homotopy_seminar/   Abstract:  The real $\mathrm{K}$-theory spectrum $\mathrm{KO}$ is "almost complex oriented''. Here are a collection of properties that demonstrate this:   (1) $\mathrm{KO}$ is the $C_2$ fixed points of a complex oriented cohomology theory $\mathrm{KU}$.   (2) Complex oriented cohomology theories have trivial Hurewicz image, whereas $\mathrm{KO}$ has a small Hurewicz image -- it detects $\eta$ and $\eta^2$.   (3) Complex oriented cohomology theories receive a ring map from $\mathrm{MU}$. $\mathrm{KO}$ receives no ring map from $\mathrm{MU}$ but it receives one from $\mathrm{MSU}$.   (4) If $E$ is a complex orientable cohomology theory, every complex vector bundle $V$ is $E$-orientable. Not every complex vector bundle $V$ is $\mathrm{KO}$-orientable, but $V\oplus V$ and $V^{\otimes 2}$ are.   Higher real $E$ theory $\mathrm{EO}$ is an odd primary analogue of $\mathrm{KO}$. At $p=3$, $\mathrm{EO}$ is closely related to $\mathrm{TMF}$. $\mathrm{EO}$ is defined as the $C_p$ fixed points of a complex oriented cohomology theory, and it has a small but nontrivial Hurewicz image, so it satisfies analogues of properties (1) and (2). I prove that it also satisfies analogues of properties (3) and (4). In particular, I produce a unital orientation map from a Thom spectrum to $\mathrm{EO}$ and prove that for any complex vector bundle $V$ the bundles $pV$ and $V^{\otimes p}$ are complex oriented. MW 154 Department of Mathematics math@osu.edu America/New_York public
Speaker: Hood Chatham (MIT)
 
Title: An Orientation Map for Higher Real E-theory
 
 
Abstract:  The real $\mathrm{K}$-theory spectrum $\mathrm{KO}$ is "almost complex oriented''. Here are a collection of properties that demonstrate this:
 
(1) $\mathrm{KO}$ is the $C_2$ fixed points of a complex oriented cohomology theory $\mathrm{KU}$.
 
(2) Complex oriented cohomology theories have trivial Hurewicz image, whereas $\mathrm{KO}$ has a small Hurewicz image -- it detects $\eta$ and $\eta^2$.
 
(3) Complex oriented cohomology theories receive a ring map from $\mathrm{MU}$. $\mathrm{KO}$ receives no ring map from $\mathrm{MU}$ but it receives one from $\mathrm{MSU}$.
 
(4) If $E$ is a complex orientable cohomology theory, every complex vector bundle $V$ is $E$-orientable. Not every complex vector bundle $V$ is $\mathrm{KO}$-orientable, but $V\oplus V$ and $V^{\otimes 2}$ are.
 
Higher real $E$ theory $\mathrm{EO}$ is an odd primary analogue of $\mathrm{KO}$. At $p=3$, $\mathrm{EO}$ is closely related to $\mathrm{TMF}$. $\mathrm{EO}$ is defined as the $C_p$ fixed points of a complex oriented cohomology theory, and it has a small but nontrivial Hurewicz image, so it satisfies analogues of properties (1) and (2). I prove that it also satisfies analogues of properties (3) and (4). In particular, I produce a unital orientation map from a Thom spectrum to $\mathrm{EO}$ and prove that for any complex vector bundle $V$ the bundles $pV$ and $V^{\otimes p}$ are complex oriented.

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