Unless I am grossly misunderstanding your notation, I have always seen RA written with the operator first. Some examples:
https://cs186berkeley.net/notes/note6/
https://web.wlu.ca/science/physcomp/ikotsireas/CP465/W1-Intr...
https://cs186berkeley.net/notes/note6/
https://web.wlu.ca/science/physcomp/ikotsireas/CP465/W1-Intr...
A common misconception (that SQL is a realization of RA instead of barely based on it).
In RA, is in fact `Relation > Operator`