left associative with precedence 55
for @{ 'compose $a $b }.
-notation "hvbox(U break ↓ V)" non associative with precedence 80 for @{ 'fintersects $U $V }.
+notation "↓a" with precedence 55 for @{ 'downarrow $a }.
+
+notation "hvbox(U break ↓ V)" non associative with precedence 55 for @{ 'fintersects $U $V }.
+
+notation "↑a" with precedence 55 for @{ 'uparrow $a }.
+
+notation "hvbox(a break ↑ b)" with precedence 55 for @{ 'funion $a $b }.
notation "(a \sup b)" left associative with precedence 60 for @{ 'exp $a $b}.
notation "s \sup (-1)" with precedence 60 for @{ 'invert $s }.