Contextuality without access to a tomographically complete set

The operational approach to contextuality due to Spekkens requires finding operationally equivalent preparation procedures. Previously these have been obtained by demanding indistinguishably under a set of measurements taken to be tomographically complete. However, there may in fact be other measurements in the true tomographically complete set, which could break the operational equivalences and hence eliminate the putative contextuality. I will sketch a proof of contextuality that is immune to this effect for a given number of unknown measurements in the tomographically complete set, which allows contextuality to be demonstrated with weaker assumptions. My talk will be based on joint work with LĂ­dia del Rio and Bettina Meyer.