Hint for authors: when discussing linear algebra (or really most other kinds of math), follow normal conventions. In this case, the convention would be that - (the minus sign) means subtraction. It does not mean "and also", especially when you sandwich it between two variables that represent matrices. I read the paper with much head scratching all the way through sections 1 and 2 and part of 3 before I figured out th…
A n-tuple notation would have been more readable and mathematically accurate like (Q=K, V), (Q, K=V), and (Q=K=V).