• + 1 comment

    I'm still learning lambda calculus, so please correct me if my logic is wrong. But here is my understanding of the probem:

    If you just take the inner part of the expression and apply beta reduction, you get:

    (λx.(f (x x)))(λx.(f (x x)))
    =(f (x x))[x:=(λx.(f (x x)))]
    =(f ((λx.(f (x x)))(λx.(f (x x)))))
    

    Which is more complex than the original function, so the reduction process doesn't terminate.