目：Ground generation

间：2018.05.22（星期二）, 14:00--16:00

点：数学院南楼N913

: Usuba recently showed that if \kappa is extendible, then the \kappa-mantle of  V is the smallest ground of V. Here, W is a ground of V iff V is a forcing extension of W, W is a \kappa-ground of V iff V is a forcing extension of W via a forcing of size < \kappa, and the \kappa-mantle of V is the intersection of all \kappa-grounds of V. We identified a similar phenomenon if V=L[E] is an extender model: We present the nice argument why the Varsovian model derived from a system of grounds of L[E] is itself a gound of L[E]. We won't presuppose knowledge of inner model theory. This is joint work with Sargsyan and Schlutzenberg.