4. Group trisections

Problem 4.1.
Use the theory of group trisections to find invariants of $4$manifold trisections. 
Problem 4.3.
Adapt group trisections to the setting of bridge trisections and use it to get invariants of knotted surfaces in $S^4$. 
Problem 4.4.
Accourding to a classical theorem by Wall, any two homotopoy equivalent, simply connected smooth closed $4$manifolds $X$ and $Y$ become diffeomorphic after stabilizing by taking connected sums with some number of $S^1\times S^2$’s. What does it says about trisections of the trivial group?
Cite this as: AimPL: Trisections and lowdimensional topology, available at http://aimpl.org/trisections.