Re: [sage-devel] Elements of finitely presented groups: hash function

2015-10-02 Thread mmarco
That would be an improvement, but still wouldn't be a solution. At some point, we have to live with the fact that comparison in finitely presented groups will only work reliably if we are lucky. What we can do is try to make the set of "lucky" groups bigger. And at some point that will come at

Re: [sage-devel] Elements of finitely presented groups: hash function

2015-10-02 Thread Nils Bruin
On Friday, October 2, 2015 at 5:02:43 AM UTC-7, vdelecroix wrote: > > important ingredient: there is no normal form in general! This is an > undecidable problem... there is no algorithm that takes as input a > presentation and outputs whether this group has more than one element. > > Though, the

Re: [sage-devel] Elements of finitely presented groups: hash function

2015-10-02 Thread mmarco
Ups, I emailed my answer to Nathan and now I am no longer in my office so I have no access to it. Can you please paste it here? -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send

Re: [sage-devel] Elements of finitely presented groups: hash function

2015-10-02 Thread Vincent Delecroix
important ingredient: there is no normal form in general! This is an undecidable problem... there is no algorithm that takes as input a presentation and outputs whether this group has more than one element. Though, there are some results about specific presentations (e.g. only one relation, sm