150 reputation
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visits member for 3 years, 5 months
seen Aug 29 at 14:21

Jul
2
awarded  Curious
May
12
awarded  Nice Question
Jan
23
awarded  Famous Question
Sep
18
asked Is there a geometrical proof of the impossibility of squaring the circle?
Jan
23
awarded  Notable Question
Oct
17
awarded  Popular Question
Jun
26
accepted Brouwer's Fan Theorem
Jun
26
accepted What is the solution of cos(x)=x?
May
21
comment Which automata recognise the algebraic numbers?
Ok, this probably sheds more light on my question cstheory.stackexchange.com/questions/10495/…
May
21
comment Which automata recognise the algebraic numbers?
I go for both..;) I would be just interested in any kind of information on the relation between algebraic numbers and automata theory. Can the algebraic numbers somehow be characterised by some automata class? If the question is trivial or too vague I would also be happy with some textbook.. It is just the case that I cannot find anything on this anywhere..
May
21
comment Which automata recognise the algebraic numbers?
The computable numbers are the real numbers computable by a Turing machine. So I am looking for something like "The algebraic numbers are the real numbers computable by ...". Basically, anything on the relation of algebraic numbers and automata would be of interest to me.
May
21
asked Which automata recognise the algebraic numbers?
Feb
16
awarded  Scholar
Feb
16
accepted Halting problem and universality
Feb
16
comment Halting problem and universality
Thanks for the answers!
Feb
15
comment Halting problem and universality
Ah ok I see. But in your first answer you wrote: "if you have an unknown class of machines and know only that they cannot solve the halting problem [...] then you CAN conclude that there's an universal machine among them." So I guess you meant "cannot" not "can"? And what about the other direction? (If you have an unknown class of countably infinite many machines and you know that there is a universal machine among them, can you conclude that they cannot solve the halting problem?)
Feb
14
comment Are all proofs “short enough” to be computed?
I am not sure whether infinitary logic can that easily be dismissed. Check out this wikipedia article en.wikipedia.org/wiki/Infinitary_logic
Feb
14
comment Halting problem and universality
I am not sure if I get your answer. I try to reformulate the question more precisely. Assume you have an unknown class of countably infinite many machines. Then you say that if you know that they cannot solve the halting problem, there is an universal machine among them, but the converse (if you know that there is an UM among them, then they cannot solve the halting problem) does not hold?
Feb
13
asked Halting problem and universality
Aug
27
comment Formalizing metamathematics
Thanks for the link!