hardmath

Knoxville, TN

uclue.com

Age: 61

Enjoys programming in Prolog.

Richard O'Keefe: "Prolog is an efficient programming language because it is a very stupid theorem prover."

15m
comment Paradoxical Game Show Problem
Please add some content to this. While it is an old puzzle, posting a link-only Answer is discouraged. Not only does the dependence on a single link risk breakage, it helps Readers to evaluate the usefulness of following a link if a clear explanation of what is found there is given.
1h
reviewed Leave Open Does there exist a pair $(i,j)$ such that $x_{i}(1-x_{j})$ and $x_{j}(1-x_{i})$ are not greater than $\frac{1}{4\cos^{2}\frac{\pi}{n+1}}$?
1h
comment An optimization problem involving orthogonal matrices
Please explain how this "might help". A link-only Answer risks becoming obsolete as links break, and it is advantageous to the Reader to have a clear expectation of what they would find if the link were followed.
1h
reviewed Reviewed If $\vec r = x \hat i + y \hat j + z \hat k$ and $r =| \vec r |$ show that $curl [f(r) \vec r] = 0$
1h
comment If $\vec r = x \hat i + y \hat j + z \hat k$ and $r =| \vec r |$ show that $curl [f(r) \vec r] = 0$
It seems like something is missing from the problem. To show $\nabla f(r) \times \vec{r} = 0$ we would need either that the two vectors are parallel or that one of them has zero magnitude. The latter possibility is not excluded by the Question, but neither does it find much justification.
3h
comment Logic programming - Is subset with only one function symbol Turing - complete?
@Nancy: If you visit chat.stackoverflow.com, then I think I can give you write access to the chat. I've already given you read access.
3h
comment Logic programming - Is subset with only one function symbol Turing - complete?
@Nancy and anyone else interested: I created a chat room for this topic to clarify what exactly is meant, and I upvoted Nancy's Q since I suspect 20 reputation are required to post in chat.
10h
reviewed Leave Open Is this proposition about $L^2$ functions correct?
10h
reviewed Leave Open Proving the divergence of a sequence
10h
reviewed Close Solving second order homogenous differential equation
10h
reviewed Leave Open Proof of an inequality
10h
reviewed Close Did I really fail the Gram Shmidt procedure, or the website had an error? linear algebra
13h
reviewed Looks Good Existence of a function with certain integral properties
13h
reviewed Close Two measures having the same moments
13h
reviewed Close Find $dy/dx$ where $(7x+2y)^2=6x^4y^3$
13h
comment Find $dy/dx$ where $(7x+2y)^2=6x^4y^3$
"Use implicit differentiation" should be enough to start (you should use it on both sides).
14h
comment Are algebraic structures required to satisfy axioms?
Universal algebra addresses a specialized kind of first order theories, where axioms can be expressed by equations (identities) and the language contains only function symbols (including constants) besides the "=" equality relation often lumped with the basics of predicate logic.
15h
reviewed Close Find a coset $f (= f + 22\Bbb Z)$ so that $(\Bbb Z/22\Bbb Z)^\times=U_{22} = \langle f\rangle$.
15h
reviewed Close Evaluate the limit $\lim \limits_{x \to \infty} \frac{1}{x(x+1)}$
15h
reviewed Close Proof by induction $\sum_{k=1}^{n}$ $k \binom{n}{k}$ $= n2^{n-1}$ for each natural number n
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