Circumflex to Distinguish Variable Names
From Why start at x, y, z
Some authors create new variable names by adorning well-known symbols (like \( A \)) with the upright (\( \hat{A} \)) and inverted (\( \check{A} \)) circumflex. Depending on the font, these tiny diacritical marks can be hard to discern at a glance. A particularly egregious example is found in Hinze 2012, "Generic Programming with Adjunctions" (p. 5).