notation "hvbox(\langle term 19 a, break term 19 b\rangle)"
with precedence 90 for @{ 'pair $a $b}.
+notation "hvbox(〈term 19 a, break term 19 b〉)"
+with precedence 90 for @{ 'pair $a $b}.
notation "hvbox(x break \times y)" with precedence 70
for @{ 'product $x $y}.