On Wed, Jan 22, 2014 at 10:05 AM, Martin Dias <tinchodias@gmail.com> wrote:

should

(T1 @ {#a -> #b} @ {#x -> #y}) = (T1 @ {#x -> #y} @ {#a -> #b})

?

two more:

(T1 - {#a. #b}) = (T1 - {#b. #a})

(T1 - {#a} - {#b}) = (T1 - {#b} - {#a})