# Definition of Reshetikhin-Turaev TQFT

I am studying Reshetikhin-Turaev TQFT. In their paper or in the book " Quantum invariants of knots and 3-manifolds", they first define an invariant $\tau(M)$ for a closed orientable 3-manifold $M$ and then they extend it to a TQFT.

First, let me briefly describe how to define this TQFT in the followings.

Let $(M, \partial_{-}M, \partial_{+}M)$ be a cobordism. Let $\Omega$ be a ribbon graph in $M$. To define a TQFT, we first glue standard handlebodies with standard ribbon graphs $R$ (defined below) inside to the bottom boundary $\partial_{-}M$ by a given parametrization and also glue them to the top boundary $\partial_{+}M$ by a composition of a given parametrization and reflection map.

Then we get a closed 3 manifold with a ribbon graph $\Omega'$, which is obtained by gluing $\Omega$ and $R$. We apply the invariant $\tau$ to this closed 3-manifold to obtain a TQFT.

My question is that when we glue standard handlebodies to the boundaries, how do we define a framing of ribbon graphs, which are images of $R$. We need to know framing to calculate $\tau$.

$R$ consistes of a coupon (a rectangle) and $g$ cap like bands attaching the coupon and several bands attaching one end to this coupon and the other end attached to the boundary of the handlebody. Here $g$ is a genus of the handlebody.

If a hundlebody is genus $1$, then I think the framing can be determined by the image of meridian. But if a genus is greater than $1$, I don't know how to define a framing.

The book and the paper don't mention how to define framings.

Any help is apprecited. Thank you in advance.

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A tip: Try to understand the simpler closed $3$-manifold case first, then try to see how the cobordism case is a generalization. – Neal May 18 '12 at 14:34
I just realized: you ask way too many questions! – user641 May 19 '12 at 1:29
@Neal I understand the closed 3 manifold case and I think I understand how they want to generalized. But I'm not sure how the standard ribbon graph behaves when glued by a parametrization. – Primo May 19 '12 at 2:12