Memo
Tables of symplectic actions on the K3 lattice (pdf)
In older versions (up to [v4, 29 Sep 2011]), #13, #19, #25, #37 and #62 are incorrect.
Lattices of type T (pdf)
I mean by "type T" a root lattice whose Dynkin diagram has three branches.
Resolution of a cusp singularity (pdf)
A singular point of a Hilbert modular surface defined by Q(\sqrt{5})