User Gadi A - Mathematics Stack Exchange

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	7,708 reputation	bio	website		visits	member for	2 years, 9 months
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6

32

votes

11

answers

3

kviews

How to convince a layman that the $\pi = 4$ proof is wrong?

calculus pi fake-proofs

may 29 '12 at 23:49 Donavuchi Di Vincenzo 11

8

29

votes

6

answers

1

kviews

Simple “real life” NP-hard problems?

computer-science np-complete

nov 13 at 10:54 A.Schulz 2,010

10

27

votes

7

answers

2

kviews

Uses of quadratic reciprocity theorem

number-theory quadratic-reciprocity motivation

nov 18 '10 at 18:27 T.. 8,108

3

16

votes

7

answers

1

kviews

Product of all elements in an odd finite abelian group is 1

group-theory finite-groups

apr 22 '12 at 12:06 James Auld 179

4

15

votes

3

answers

1

kviews

Primes of the form $n^2+1$ - hard?

number-theory reference-request prime-numbers open-problem

jun 7 '12 at 17:53 Community♦ 1

5

15

votes

5

answers

1

kviews

How fundamental is the fundamental theorem of algebra?

abstract-algebra polynomials terminology complex-numbers

dec 10 '11 at 10:27 Ｊ. M. 39.9k

2

14

votes

1

answer

376

views

Once and for all - “Rational numbers” - because of ratio, or because they make sense?

terminology math-history

dec 8 at 3:54 alex.jordan 9,587

4

13

votes

5

answers

2

kviews

Prime dividing the binomial coefficients

elementary-number-theory prime-numbers binomial-coefficients

feb 18 at 2:20 Bruno 7,421

2

11

votes

4

answers

1

kviews

Why an inconsistent formal system can prove everything?

logic proof-theory

jun 4 at 19:21 James Fair 3

2

10

votes

0

answers

255

views

$f(x)=\sum_{t}{x \choose t}{n-x \choose k-t}$ - even or odd?

combinatorics number-theory binomial-coefficients parity

jun 12 '12 at 14:20 Gadi A 7,708

2

10

votes

1

answer

274

views

Is Hilbert's second problem about the real numbers or the natural numbers?

logic math-history

oct 25 '11 at 12:46 Carl Mummert 26.6k

3

10

votes

1

answer

245

views

Is this similarity between trees and vector space bases just a coincidence?

linear-algebra soft-question graph-theory

aug 11 '11 at 13:49 Miha Habič 2,196

3

10

votes

7

answers

1

kviews

“Proof” that ZFC is inconsistent using Turing machines

logic fake-proofs computability

dec 24 '10 at 3:53 Zirui Wang 193

4

10

votes

3

answers

877

views

An orthonormal set cannot be a basis in an infinite dimension vector space?

linear-algebra orthonormal

dec 10 '10 at 3:44 Jonas Meyer 35.3k

1

9

votes

5

answers

504

views

Deriving the formula for the Möbius function?

combinatorics elementary-number-theory

may 17 at 10:10 Marc van Leeuwen 25.8k

1

9

votes

1

answer

349

views

Is $\mathbb{C}^*$ modulo the roots of unity isomorphic to $\mathbb{R}^+$?

group-theory complex-numbers examples-counterexamples

apr 24 '12 at 15:45 Community♦ 1

1

9

votes

3

answers

300

views

Solving the recurrence relation $A_n=n!+\sum_{i=1}^n{n\choose i}A_{n-i}$

combinatorics recurrence-relations

nov 15 '11 at 20:43 Qiaochu Yuan 121k

2

9

votes

4

answers

189

views

Bounding ${(2d-1)n-1\choose n-1}$

calculus combinatorics inequality binomial-coefficients

jun 9 '11 at 12:09 Shai Covo 17k

1

8

votes

4

answers

975

views

Famous uses of the inclusion-exclusion principle?

combinatorics big-list examples-counterexamples inclusion-exclusion

jan 25 at 20:35 Byron Schmuland 15.6k

2

8

votes

1

answer

110

views

A game played on graphs by “flipping” the state of a vertex and its neighbors

combinatorics graph-theory recreational-mathematics

jan 23 '12 at 18:45 Aryabhata 48k

2

8

votes

4

answers

734

views

Easy ways to find partial fraction representation? (via a concrete example)

algebra-precalculus partial-fractions symbolic-computation

dec 17 '11 at 7:15 Ｊ. M. 39.9k

1

8

votes

1

answer

201

views

How to show that all even perfect numbers are obtained via Mersenne primes?

number-theory prime-numbers

oct 11 '11 at 12:43 Charles 9,278

2

8

votes

3

answers

585

views

Can one avoid AC in the proof that in Noetherian rings there is a maximal element for each set?

abstract-algebra axiom-of-choice

aug 22 '11 at 16:22 zyx 12k

1

8

votes

1

answer

228

views

Constructing a finite field

abstract-algebra finite-fields computational-mathematics

jul 16 '11 at 15:42 deinst 2,856

1

8

votes

1

answer

329

views

A different proof of the insolubility of the quintic?

abstract-algebra galois-theory

nov 20 '10 at 23:21 Timothy Wagner 6,193

1

7

votes

3

answers

467

views

Simple (even toy) examples for uses of Ordinals?

set-theory examples-counterexamples ordinals

nov 8 '11 at 18:43 Martin Sleziak 20.8k

2

7

votes

1

answer

508

views

Writing the Laplacian matrix of directed graphs as product?

linear-algebra graph-theory

sep 13 '11 at 10:55 Gadi A 7,708

2

7

votes

3

answers

812

views

Finding the power series of a rational function

real-analysis combinatorics commutative-algebra

sep 14 '10 at 18:21 Hans Lundmark 14.6k

1

7

votes

3

answers

863

views

Computing the largest Eigenvalue of a very large sparse matrix?

linear-algebra matrices numerical-methods

sep 12 '10 at 10:19 Graviton 774

6

votes

1

answer

243

views

Nice riddle - is there an elegant solution [duplicate]

probability puzzle

jun 1 '12 at 16:47 André Nicolas 168k

Gadi A

94 Questions