14,992 reputation
11940
bio website math.brown.edu/~lubinj
location Minnesota
age 78
visits member for 3 years, 2 months
seen 2 hours ago

Aged mathematician


Nov
29
revised Determine the minimal polynomial of $\sqrt 3+\sqrt 5$
added 450 characters in body
Nov
28
revised Let $y^2 = x^3 + Ax + B$ be a curve and $y = m(x - x_1) + y_1$ tangent at $x_1$. Why is $x_1$ then a double root?
Complete rewrite!
Nov
7
revised Is there a rationality-preserving order isomorphism between $\mathbb{Q}$ and two disjoint open intervals?
Admitted that my “solution” of the problem was no such thing. Drat.
Nov
7
revised Is there a rationality-preserving order isomorphism between $\mathbb{Q}$ and two disjoint open intervals?
changed an insufficient answer to a sufficient one, I hope.
Oct
24
revised Question about laurent series
left off a crucial minus sign in a fmla
Sep
17
revised finding “exp(1)” in the p-adic numbers
slipped and gave the formal-group logarithm, not the genuine one. Now corrected
Aug
25
revised Disproving an “almost true” trigonometric identity
Gave an alternate, longer, less magical, proof.
Aug
25
revised Disproving an “almost true” trigonometric identity
deleted 14 characters in body
Aug
25
revised Disproving an “almost true” trigonometric identity
Correct two even more embarrassing careless errors
Aug
24
revised Disproving an “almost true” trigonometric identity
corrected an embarrassing error of elementary-school arithmetic.
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.