Speaker
Kyoji Saito
Description
It is well-known that there exist semi-infinite Hodge structure associated to finite or
elliptic root systems (which describes the lattice of vanishing cycles for either simple
or elliptic root systems). Recently, we found that the semi-infinite Hodge structure
exist for hyperbolic root systems of rank 2. This is a surprise, since the hyperbolic
root systems do not have geometric origin so the they behaves quite differently than
the above classical cases (e.g. some eigenvalues of monodromy are not root of unity
but real). In the present talk, we will describe the construction down to the earth.
