Daniele Orti: What about dynamics?  No matter. Pure gravity there is not much to calculate.

Nic: Well the correct CFT dual would have matter states.  But we’re not sure how to get there.

[From the back]

We can look at asymptotic behavior, which we can specify, and that leads to AdS results.

Chris Wuthrich: I don’t quite understand the correspondence we have.  Are you saying that the notions of equivalence we have are not applicable?

Nic: It may be that we’re not at a sufficiently advanced level.  The categorical equivalence fails in other cases.

Another question?

CW: No, I was just saying I didn’t understand. Would you like to comment? [laughter]

Nic: Categorical tools have been applied to holography.

Sam Fletcher: But we can weaken categorical equivalence.  We don’t even know in this case what the categories are in this case to relate.  Would need to be sure of what the categories are.

Jeremy Butterfield: An old man question: long ago, the syntactic view said two theories were equivalent if they were (mtually) definitionally extensible. Halvorson would reject this, since allows labels to stick to structures [poor paraphrase].  But can model isomorphism not be improved so that having the same models i.e. having each other as one’s definitional equivalent?

[Interjection] Clark Glymour has recently responded to Halvorson somewhere along these lines.

Nic: I agree with JNB. But would be hard to write out syntactically.  Category of models is useful as it is native to modern math.  This is a good thing. 

Exits, for taxi awaiting outside.  [Applause]