12,439 reputation
11332
bio website math.brown.edu/~lubinj
location Minnesota
age 77
visits member for 2 years, 9 months
seen 3 mins ago

Aged mathematician


Jul
11
revised Is $4x^2-4x+2$ surjective?
yet another embarrassing slip
Jul
7
revised Determine whether the intersection of surfaces is a parabola
Corrected an embarrassing slip.
Jul
2
revised I need a relation which is not reflexive, not symmetric, and not transitive
corrected mathematical error pointed out by amalloy
Jun
30
revised Show that $(x-\alpha)(x-\overline{\alpha})$ is a also a factor of $p(t)$ over the complex numbers
Corrected an embarrassing typo.
May
12
revised In modular arithmetic is $m^{1/x}$ =! $(m^x)^{-1}$
Changed $\mathbb{Z}^3$ to $\mathbb{Z}_3$.
May
7
revised What is $x^2+4xy+y^2=1$ an equation of??
Gave a quick response in EDIT 2 to the particular question.
Apr
27
revised Let $K = \mathbb{Q}(\alpha)$ where $\alpha$ is a root of the polynomial $x^3 + 2x + 1$, and let $g(x) = x^3 + x + 1$. Does $g(x)$ have a root in $K$?
Gave second argument, slightly more elementary, and complete.
Apr
16
revised General methods for solving p-adic inequality $|a^2+b|_{p}<p^{-k}$ for $a\in \mathbb{Z}$
clarification
Apr
14
revised $2$-adic inverse of $3$
Expanded considerably on my answewr, explaining a technique for $p$-adic hand computation.
Mar
20
revised Geometric meanings of hyperbolic cosinus and sinus
Made a long explanation from a primitive viewpoint of how to measure distance on the hyperbolic plane in a canonical way.
Mar
18
revised Basic Question on Field Theory - Hopefully to Illustrate Several Concepts
expanded to cover both parts of the question
Jan
18
revised Find basis of $\mathbb{Q}(\sqrt{2}+\sqrt[3]{4})$
corrected a sign error in the denominator of the last fraction
Dec
6
revised Why do we have to do the same things to both sides of an equation?
added 10 characters in body
Nov
20
revised Finding injective mapping $f : \{0,1,2\}^\mathbb{N} \rightarrow \{0,1\}^\mathbb{N}$
respond to OPs request for proof that the function is one-to-one
Nov
20
revised Finding injective mapping $f : \{0,1,2\}^\mathbb{N} \rightarrow \{0,1\}^\mathbb{N}$
Took me a long time to understand his attempted answer. Deleted my answer, and wrote out what he was looking for.
Nov
18
revised Compositum of finite field extensions
OP asked for a complete proof
Nov
6
revised Finite polynomial rings and degree of polynomial
changed “$x^5=x^0$” to $x^5\ne x^0$, which I’m sure was the respondent’s intention.
Oct
19
revised finding the inverse of function. the domain is given and the question requires to find the inverse.
Corrected a serious error and other problems arising from misreading the given question.
Oct
11
revised can a great circle route be predicted from initial condition?
corrected a serious and confusing typo, I once had $\lambda$ when I meant $\theta$
Sep
11
revised Why are the order-of-operations conventions good?
corrected a typo, turning an ungrammaticality into good language