Comment by Traubenfuchs
3 years ago
I remember memorizing how to solve (reduce? resolve? expand?) lambda calculus expressions by hand that went over multiple lines for my degree but I never had the faintest clue what it is and why I was learning this and quickly forgot how to do it.
> solve (reduce? resolve? expand?)
Reduction (in particular "beta-reduction") is essentially 'calling a function with an argument' (just defined in a precise, mathematically-rigorous way). Since lambda calculus only has functions (AKA "lambdas"), "reducing an expression" is another way of saying "running/executing a program".
"Expansion" would be going the other way; e.g. introducing an abstraction layer which, when reduced/executed, would result in the original expression.