User blog comment:Wythagoras/Dollar function part 2/@comment-5029411-20130608134542/@comment-5150073-20130608154050

I can note that {a,a / 2} is not roughly {a,a [1 [2 --| 2] 2] 2} ~ {X,X,a} & a.

{a,a / 2} ~ {a,a [1 [1 --| 1 --| 2] 2] 2}.