Under physicalism, existence consists of mathematical patterns. Everything that exists is a mathematical object as described by whatever physical theory is a true description of the universe.
If physicalism is true, then everything that exists is isomorphic to some mathematical construct. A mathematical construct is something such as a natural number, a set, a graph, etc.
If physicalism is false, it can still be the case that existence consists of mathematical patterns. Let us call this view “mathematicalism.”
Mathematicalism. Everything that exists is isomorphic to some mathematical construct.
If physicalism is true, then mathematicalism is true. But mathematicalism can still be true if physicalism is false. Thus, for instance, things such as souls, angels, and demons may exist, and be mathematical patterns. It might be that the mind is an entity distinct from the brain, but nonetheless a mathematical pattern like the brain.