Wikipedia:Reference desk/Archives/Mathematics/2021 August 13

= August 13 =

Lambda expressions
This paper from Cornell (http://www.cs.cornell.edu/courses/cs312/2008sp/recitations/rec26.html) states that the following two lambda expressions are equivalent:

$λx. λy. y$

$λx.(x (λy.y))$

I'm not sure why they are equivalent. The first lambda expression takes an arbitrary variable as a parameter and returns the identity function. The second one takes a variable and applies it to the identity function. How are those the same thing? -- Puzzledvegetable Is it teatime already?  02:32, 13 August 2021 (UTC)


 * It is clearly a (very confusing) typo. The first expression is meant to read $λx.x λy.y$. The expressions are then not merely equivalent, but the same, just like in high-school algebra $a + b × c$ is "the same" as $a + (b × c)$. --Lambiam 07:32, 13 August 2021 (UTC)