TYPE syntax variable string (e.g. "x", "y") application (E E') (where E and E' are both lambda expressions) abstraction \x.E (where x is a variable and E a lambda expression)or using BNF:
LAMBEXPR :: = VARIABLE | (LAMBEXPR LAMBEXPR) | ("\" VARIABLE "." LAMBEXPR) Note that the two pieces of concrete syntax (the period and lambda symbols) have been explicitly quoted.Which of the following are legal lambda expressions:
1. x