I am a bachelor of education and recently, a game-theoretic solution concept piqued my research interest, at least for the purpose of research-writing as a personal hobby. In cooperative game theory, we have the so-called Shapley Value (and in the context of education, it is seen to be useful to "solve" the Freeloader Problem and the Fair Grade Allocation Problem when teachers assign marks or grades to students working together as a group).
Now, I am attempting to put forth a corollary of the Shapley axioms, and I am calling it the "Positive Correlation Axiom". This claim, I think, is intuitive and somehow "obvious". I am stuck on how I can establish such claim using a formal proof. So,
Suppose I am trying to show the existence of a positive correlation between $\textit{A}$ and $\textit{B}$, how can I prove such theorem?
Any help, be it a proof outline or a complete proof, is much appreciated.