A trisection is a decomposition of a 4-manifold into three
1-handlebodies. It can be represented by a diagram consisting of a
surface and simple closed curves, known as a trisection diagram. From
this decomposition, we can define several invariants of 4-manifolds.
In this talk, we will introduce some of them. On the other hand, there
is another way to describe 4-manifolds, which is called a shadow. In
this talk, we will explore the relationship between the invariants
defined using trisection diagrams and shadows.