Infinite dimensional perfect set theorems

What largeness and structural assumptions on A ⊆ [R]ω can guarantee the existence of a non-empty perfect set P ⊆ R such that [P ]ω ⊆ A? Such a set P is called A-homogeneous. We show that even if A is open, in general it is independent of ZFC whether for a cardinal κ, the existence of an A-homogeneous set H ∈ [R]κ implies the existence of a non-empty perfect A-homogeneous set. On the other hand, we prove an infinite dimensional analogue of Mycielski’s Theorem: if A is large in the sense of a suitable Baire category-like notion then there exists a non-empty perfect Ahomogeneous set. We introduce fusion games to prove this and other infinite dimensional perfect set theorems. Finally we apply this theory to show that it is independent of ZFC whether Tukey reductions of the maximal analytic cofinal type can be witnessed by definable Tukey maps.