
Re: Mathematics in brief
Posted:
Dec 10, 2012 12:32 AM


On Dec 10, 12:21 am, WM <mueck...@rz.fhaugsburg.de> wrote: > On 9 Dez., 21:19, Zuhair <zaljo...@gmail.com> wrote: > > > > > > > > > > > On Dec 9, 10:59 pm, WM <mueck...@rz.fhaugsburg.de> wrote: > > > > On 9 Dez., 20:37, Zuhair <zaljo...@gmail.com> wrote: > > > > > > Only a countable subset can be represented by the Binary Tree. The > > > > > reason is that no path is really actually infinite. > > > > > Then you are not addressing what Cantor was speaking about, he is > > > > speaking about reals represented by ACTUALLY infinite sequences (paths > > > > in your case). It is clear that the set of all reals represented by > > > > FINITE sequences is countable, but those are just a very small subset > > > > of the set of all reals. > > > > > If one assumes Actual infinity, then it is easy to recover the > > > > diagonal path from any bijection between the reals and the set of all > > > > paths of the infinite binary tree, and this will be a path that is not > > > > present in the tree of course. > > > > Then you are wrong from the scratch. Every real number has a > > > representation by an infinite sequence (= infinite path of nodes in > > > the tree). But as my proff shows I construct the whole Binary Tree by > > > countably many paths. There are not more nodes available to add > > > further paths. > > > > >You will need uncountably many infinite > > > > binary trees to recover all the reals. > > > > That is purest nonsense. And it has nothing to do with Cantor's > > > diagonal which is of course an infinite sequence of digits > > > corresponding to a path in the Binary Tree. > > > Yes corresponding to an ACTUAL infinite path in the Binary Tree, which > > is something that you already refuse to address. > > No, you misunderstood. I construct the actually infinite Binary Tree > by actually infinite paths like "every finite path which is appended > by an actually infinite sequence of 000..." or "every finite path > which is appended by an actually infinite sequence of 111..." or ... > Ok, now you are clear. And just to make it more clear you are claiming that the actual infinite path 101010... is a path in your actual infinity binary tree, correct.
If so what is the proof that ALL reals belong to that tree?
And what is the proof that the number of paths in that tree is countable? I can see that the number of paths in any FINITE binary tree is less than the number of its nodes? but can that feature survive at infinite level? and what is the proof? I do see that the number of nodes in your tree is countable. But would it follow that the number of paths must be so at infinite level?
How I see matters is that if I assume that there is a bijection between N and the set of all infinite paths in your tree, then I can easily construct a diagonal using Cantor's argument, and this diagonal would provably be a path that is not in that Tree. So either your tree must have uncountably many paths (with countably many nodes) or your tree has countably many paths but is incomplete, i.e. there are infinite binary paths that are not paths of it.
Zuhair

