non associative with precedence 40
for @{ 'not $a }.
+notation > "hvbox(a break \liff b)"
+ left associative with precedence 25
+for @{ 'iff $a $b }.
+
+notation "hvbox(a break \leftrightarrow b)"
+ left associative with precedence 25
+for @{ 'iff $a $b }.
+
+
notation "hvbox(\Omega \sup term 90 A)" non associative with precedence 70
for @{ 'powerset $A }.