Klockan3
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There are some hard stuff, but a wast majority of it is just menial exercising of normal techinques used for doing proofs.morphism said:Fair enough. However, in most courses you do (or, at least, should) get challenging exercises. If not, then there's something not quite right about the courses you've been taking.
I did this one in my first year, with just the Euclidean algorithm above high school level:
F(n) is the n'th number of the Fibonacci sequence. Ie, F(0)=0, F(1)=1, F(n+2)=F(n+1)+F(n)
Prove that GCD(F(N),F(M))=F(GCD(N,M))
Assume there is an ideal that isn't principal. This ideal needs to be a sub ideal to a max ideal since all maximal ideals are principal. Since we have an unique factorization this ideal will look exactly like the original ring but with a factor of the generator extra in every object. This means that any sub ideal of this ideal will have a direct correlation with the ideals of the original ring and thus the maximal sub ideals must then also be principal. Which in turn means that our ideal we are looking for must also be a sub ideal of one of those principal ideals.morphism said:Let R be a unique factorization domain in which every maximal ideal is principal. Prove that every ideal of R is principal.
I've provided Wikipedia links to all the appropriate definitions. If you attempt this problem, then I think you will agree that it requires a bit more than just a knowledge of these defintions.
Thus this process repeats ad infinitum and as such we can never find an ideal which is not principal.
There certainly are more than one way to solve most of these, but usually you have gone through ways to solve things that are very similar to what you are supposed to solve now and just minor adjustments are needed.DukeofDuke said:Well, you need some set point to compare to. If you let that set point be the computational mathematics that most people consider maths to be (some calculus, diff eq, maybe basic stat) then yes, the classes I mentioned are indeed quite nontrivial. There are certainly many ways to those types of proofs- which is why me and my peers come up with completely different methods at times. So its pretty fallacious to say you're given a set of instructions, almost a function, and asked to perform that function on a problem.
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