Here are some letters to Alan Weinstein written between 1998 and 2000. Use with care.
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###### contents:

- definition and classification of exact Courant algebroids (CAs), their origin in 2dim variational problems, suggested a connection with gerbes
- review of Poisson-Lie T-duality, the exact CA over a Lie group, Dirac structures as boundary conditions (D-branes)
- local description of transitive CAs, connection with central extensions
- classification of transitive CAs (via transitive Lie algebroids with vanishing 1st Pontriagin class), reductions of CAs
- the connection between CAs and gerbes (via conducting bundles)
- a canonical construction of a nilpotent Dirac operator generating (any) CA (following A.Alekseev and P.Xu); Clifford and Grassmann algebroids
- CA = symplectic dg-manifold with symplectic form of degree 2; the connection between CAs and gerbes via dg manifolds
- integration of Lie algebroids/Courant algebroids/bialgebroids/etc. using the ideas of Sullivan's rational homotopy theory and the AKSZ construction of TQFTs (integration=homotopy)
- a double symplectic groupoid via moduli spaces of flat connections
- remarks on the problem of calculating H(B Gamma) using the Lie algebroid of Gamma and differential forms