Karl Kronenfeld
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 Mar21 awarded Yearling Dec21 awarded Constituent Dec9 awarded Caucus Dec3 comment Nobody told me that self teaching could be so damaging… I get the sense that you feel you know every aspect of the subjects you are taking. There is absolutely no way that is true; you simply haven't looked hard enough to find the interesting stuff. Often times the book will have exercises geared toward the more advanced reader at the end of its exercise sets, see if that is true for your textbooks. Also, look for patterns in your problems sets or see if there is some abstract result that solves your problems more efficiently or gives you deeper understanding of the answers. Dec2 comment Determine $\phi(2^{399}+1)$ My crystal ball works! Nov14 comment Determine $\phi(2^{399}+1)$ Intended answer: some very large number. Oct19 comment xy+x+y=0 What is the inverse Element? @Clayton Your confusion arises from mixing up the two multiplication operations. Sep30 awarded Explainer Sep24 awarded Autobiographer Sep4 comment Bisectors problem So it is just a hypothesis that N exists and B lies between M and N? Sep4 comment What is the flaw in this proof that all triangles are isosceles? You read the statement somewhere, it would help us if you indicated where you read it. Sep3 comment Bisectors problem That's what I guessed, chen h.; however consider a 45-45-90 triangle with legs AC, BC. Then the bisector of the supplementary angle of ACB is parallel to AB. Sep3 comment Bisectors problem Just wondering, what is the supplementary angle of a given angle? I took a guess, but it does not always happen that B lies between M and N with my choice. Sep1 comment Right-adjoint to the inverse image functor I discovered the right-adjoint $g$ by considering two simple examples. Let $f_1$ be the function from the set of two points to the singleton set. Let $f_2$ be the function $\{a,b,c\}\to\{u,v\}\colon a,b\mapsto u,c\mapsto v$. Perhaps these considerations will help you too. Sep1 comment question about $Spec(A)$ in Atiyah's book Introduction to Commutative Algebra @claire Yep, there is no such thing as an infinite sum. We sometimes abuse notation and write $\sum_{i\in I}f_ig_i$, $g_i\in A$ and all but finitely many of the $g_i$ are zero. Sep1 comment question about $Spec(A)$ in Atiyah's book Introduction to Commutative Algebra @claire You need to be a little more careful, since you may notice that your description allows for infinite sums in $A$ (something that makes no sense in your random ring $A$). Sep1 answered question about $Spec(A)$ in Atiyah's book Introduction to Commutative Algebra Jul16 comment Calculating a Factorial Base Representation While it is hard to be more explicit in your statement of the algorithm, a proof of it would be nice (I have proven it myself--I am just suggesting an improvement for your answer) Jun27 comment Definition of relatively prime in UFD´s BTW, it's great that you are comparing the definitions from two sources. Jun27 comment Definition of relatively prime in UFD´s If it was not a Unique Factorization Domain, you would be 100% correct.