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Are there infinite number of Mersenne Primes? ★★★★

Author(s):

Conjecture   A Mersenne prime is a Mersenne number \[ M_n  = 2^p  - 1 \] that is prime.

Are there infinite number of Mersenne Primes?

Keywords: Mersenne number; Mersenne prime

Erdős–Straus conjecture ★★

Author(s): Erdos; Straus

Conjecture  

For all $ n > 2 $, there exist positive integers $ x $, $ y $, $ z $ such that $$1/x + 1/y + 1/z = 4/n$$.

Keywords: Egyptian fraction

Match Masters Coins Cheats 2024 Update (FREE!!) ★★

Author(s):

Match Masters Coins Cheats 2024 Update (FREE!!)

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End-Devouring Rays

Author(s): Georgakopoulos

Problem   Let $ G $ be a graph, $ \omega $ a countable end of $ G $, and $ K $ an infinite set of pairwise disjoint $ \omega $-rays in $ G $. Prove that there is a set $ K' $ of pairwise disjoint $ \omega $-rays that devours $ \omega $ such that the set of starting vertices of rays in $ K' $ equals the set of starting vertices of rays in $ K $.

Keywords: end; ray

Genshin Impact Cheats Generator 2024 Update (FREE) ★★

Author(s):

Genshin Impact Cheats Generator 2024 Update (FREE)

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MSO alternation hierarchy over pictures ★★

Author(s): Grandjean

Question   Is the MSO-alternation hierarchy strict for pictures that are balanced, in the sense that the width and the length are polynomially (or linearly) related.

Keywords: FMT12-LesHouches; MSO, alternation hierarchy; picture languages

Are different notions of the crossing number the same? ★★★

Author(s): Pach; Tóth

Problem   Does the following equality hold for every graph $ G $? \[ \text{pair-cr}(G) = \text{cr}(G) \]

The crossing number $ \text{cr}(G) $ of a graph $ G $ is the minimum number of edge crossings in any drawing of $ G $ in the plane. In the pairwise crossing number $ \text{pair-cr}(G) $, we minimize the number of pairs of edges that cross.

Keywords: crossing number; pair-crossing number

The robustness of the tensor product ★★★

Author(s): Ben-Sasson; Sudan

Problem   Given two codes $ R,C $, their Tensor Product $ R \otimes C $ is the code that consists of the matrices whose rows are codewords of $ R $ and whose columns are codewords of $ C $. The product $ R \otimes C $ is said to be robust if whenever a matrix $ M $ is far from $ R \otimes C $, the rows (columns) of $ M $ are far from $ R $ ($ C $, respectively).

The problem is to give a characterization of the pairs $ R,C $ whose tensor product is robust.

Keywords: codes; coding; locally testable; robustness

"New Cheats" Subway Surfers Coins Keys Cheats Free 2024 ★★

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"New Cheats" Subway Surfers Coins Keys Cheats Free 2024

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Dice Dreams Cheats Generator Get Free Dice Dreams Cheats Generator 2024 (Brand New) ★★

Author(s):

Dice Dreams Cheats Generator Get Free Dice Dreams Cheats Generator 2024 (Brand New)

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Divisibility of central binomial coefficients ★★

Author(s): Graham

Problem  (1)   Prove that there exist infinitely many positive integers $ n $ such that $$\gcd({2n\choose n}, 3\cdot 5\cdot 7) = 1.$$
Problem  (2)   Prove that there exists only a finite number of positive integers $ n $ such that $$\gcd({2n\choose n}, 3\cdot 5\cdot 7\cdot 11) = 1.$$

Keywords:

Nonseparating planar continuum ★★

Author(s):

Conjecture   Does any path-connected, compact set in the plane which does not separate the plane have the fixed point property?

A set has the fixed point property if every continuous map from it into itself has a fixed point.

Keywords: fixed point

Stable set meeting all longest directed paths. ★★

Author(s): Laborde; Payan; Xuong N.H.

Conjecture   Every digraph has a stable set meeting all longest directed paths

Keywords:

Counterexamples to the Baillie-PSW primality test ★★

Author(s):

Problem  (1)   Find a counterexample to Baillie-PSW primality test or prove that there is no one.
Problem  (2)   Find a composite $ n\equiv 3 $ or $ 7\pmod{10} $ which divides both $ 2^{n-1} - 1 $ (see Fermat pseudoprime) and the Fibonacci number $ F_{n+1} $ (see Lucas pseudoprime), or prove that there is no such $ n $.

Keywords:

The three 4-flows conjecture ★★

Author(s): DeVos

Conjecture   For every graph $ G $ with no bridge, there exist three disjoint sets $ A_1,A_2,A_3 \subseteq E(G) $ with $ A_1 \cup A_2 \cup A_3 = E(G) $ so that $ G \setminus A_i $ has a nowhere-zero 4-flow for $ 1 \le i \le 3 $.

Keywords: nowhere-zero flow

A generalization of Vizing's Theorem? ★★

Author(s): Rosenfeld

Conjecture   Let $ H $ be a simple $ d $-uniform hypergraph, and assume that every set of $ d-1 $ points is contained in at most $ r $ edges. Then there exists an $ r+d-1 $-edge-coloring so that any two edges which share $ d-1 $ vertices have distinct colors.

Keywords: edge-coloring; hypergraph; Vizing

Matchings extend to Hamiltonian cycles in hypercubes ★★

Author(s): Ruskey; Savage

Question   Does every matching of hypercube extend to a Hamiltonian cycle?

Keywords: Hamiltonian cycle; hypercube; matching

Kneser–Poulsen conjecture ★★★

Author(s): Kneser; Poulsen

Conjecture   If a finite set of unit balls in $ \mathbb{R}^n $ is rearranged so that the distance between each pair of centers does not decrease, then the volume of the union of the balls does not decrease.

Keywords: pushing disks

Fishing Clash Cheats Generator IOS Android No Verification 2024 (Tips Strategy) ★★

Author(s):

Fishing Clash Cheats Generator IOS Android No Verification 2024 (Tips Strategy)

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Strict inequalities for products of filters

Author(s): Porton

Conjecture   $ \mathcal{A} \times^{\mathsf{\ensuremath{\operatorname{RLD}}}}_F \mathcal{B}   \subset \mathcal{A} \ltimes \mathcal{B} \subset \mathcal{A}   \times^{\mathsf{\ensuremath{\operatorname{RLD}}}} \mathcal{B} $ for some filter objects $ \mathcal{A} $, $ \mathcal{B} $. Particularly, is this formula true for $ \mathcal{A} = \mathcal{B} = \Delta \cap \uparrow^{\mathbb{R}} \left( 0 ; +   \infty \right) $?

A weaker conjecture:

Conjecture   $ \mathcal{A} \times^{\mathsf{\ensuremath{\operatorname{RLD}}}}_F \mathcal{B}   \subset \mathcal{A} \ltimes \mathcal{B} $ for some filter objects $ \mathcal{A} $, $ \mathcal{B} $.

Keywords: filter products

Negative association in uniform forests ★★

Author(s): Pemantle

Conjecture   Let $ G $ be a finite graph, let $ e,f \in E(G) $, and let $ F $ be the edge set of a forest chosen uniformly at random from all forests of $ G $. Then \[ {\mathbb P}(e \in F \mid f \in F}) \le {\mathbb P}(e \in F) \]

Keywords: forest; negative association

Unused Free Bloons TD Battles Cheats No Human Verification No Survey (2024 Method) ★★

Author(s):

Unused Free Bloons TD Battles Cheats No Human Verification No Survey (2024 Method)

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List Colourings of Complete Multipartite Graphs with 2 Big Parts ★★

Author(s): Allagan

Question   Given $ a,b\geq2 $, what is the smallest integer $ t\geq0 $ such that $ \chi_\ell(K_{a,b}+K_t)= \chi(K_{a,b}+K_t) $?

Keywords: complete bipartite graph; complete multipartite graph; list coloring

What is the homotopy type of the group of diffeomorphisms of the 4-sphere? ★★★★

Author(s): Smale

Problem   $ Diff(S^4) $ has the homotopy-type of a product space $ Diff(S^4) \simeq \mathbb O_5 \times Diff(D^4) $ where $ Diff(D^4) $ is the group of diffeomorphisms of the 4-ball which restrict to the identity on the boundary. Determine some (any?) homotopy or homology groups of $ Diff(D^4) $.

Keywords: 4-sphere; diffeomorphisms

Graceful Tree Conjecture ★★★

Author(s):

Conjecture   All trees are graceful

Keywords: combinatorics; graceful labeling

Frankl's union-closed sets conjecture ★★

Author(s): Frankl

Conjecture   Let $ F $ be a finite family of finite sets, not all empty, that is closed under taking unions. Then there exists $ x $ such that $ x $ is an element of at least half the members of $ F $.

Keywords:

Subgroup formed by elements of order dividing n ★★

Author(s): Frobenius

Conjecture  

Suppose $ G $ is a finite group, and $ n $ is a positive integer dividing $ |G| $. Suppose that $ G $ has exactly $ n $ solutions to $ x^{n} = 1 $. Does it follow that these solutions form a subgroup of $ G $?

Keywords: order, dividing

The Borodin-Kostochka Conjecture ★★

Author(s): Borodin; Kostochka

Conjecture   Every graph with maximum degree $ \Delta \geq 9 $ has chromatic number at most $ \max\{\Delta-1, \omega\} $.

Keywords:

Antidirected trees in digraphs ★★

Author(s): Addario-Berry; Havet; Linhares Sales; Reed; Thomassé

An antidirected tree is an orientation of a tree in which every vertex has either indegree 0 or outdergree 0.

Conjecture   Let $ D $ be a digraph. If $ |A(D)| > (k-2) |V(D)| $, then $ D $ contains every antidirected tree of order $ k $.

Keywords:

MONOPOLY GO Cheats Generator 2024 (fresh strategy) ★★

Author(s):

MONOPOLY GO Cheats Generator 2024 (fresh strategy)

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Few subsequence sums in Z_n x Z_n ★★

Author(s): Bollobas; Leader

Conjecture   For every $ 0 \le t \le n-1 $, the sequence in $ {\mathbb Z}_n^2 $ consisting of $ n-1 $ copes of $ (1,0) $ and $ t $ copies of $ (0,1) $ has the fewest number of distinct subsequence sums over all zero-free sequences from $ {\mathbb Z}_n^2 $ of length $ n-1+t $.

Keywords: subsequence sum; zero sum

Coin Master Spins Coins Cheats 2024 No Human Verification (Real) ★★

Author(s):

Coin Master Spins Coins Cheats 2024 No Human Verification (Real)

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A homomorphism problem for flows ★★

Author(s): DeVos

Conjecture   Let $ M,M' $ be abelian groups and let $ B \subseteq M $ and $ B' \subseteq M' $ satisfy $ B=-B $ and $ B' = -B' $. If there is a homomorphism from $ Cayley(M,B) $ to $ Cayley(M',B') $, then every graph with a B-flow has a B'-flow.

Keywords: homomorphism; nowhere-zero flow; tension

MONOPOLY GO Cheats Generator IOS Android No Verification 2024 (fresh method) ★★

Author(s):

MONOPOLY GO Cheats Generator IOS Android No Verification 2024 (fresh method)

Keywords:

A conjecture on iterated circumcentres ★★

Author(s): Goddyn

Conjecture   Let $ p_1,p_2,p_3,\ldots $ be a sequence of points in $ {\mathbb R}^d $ with the property that for every $ i \ge d+2 $, the points $ p_{i-1}, p_{i-2}, \ldots p_{i-d-1} $ are distinct, lie on a unique sphere, and further, $ p_i $ is the center of this sphere. If this sequence is periodic, must its period be $ 2d+4 $?

Keywords: periodic; plane geometry; sequence

Domination in cubic graphs ★★

Author(s): Reed

Problem   Does every 3-connected cubic graph $ G $ satisfy $ \gamma(G) \le \lceil |G|/3 \rceil $ ?

Keywords: cubic graph; domination

Frobenius number of four or more integers ★★

Author(s):

Problem   Find an explicit formula for Frobenius number $ g(a_1, a_2, \dots, a_n) $ of co-prime positive integers $ a_1, a_2, \dots, a_n $ for $ n\geq 4 $.

Keywords:

Reconstruction conjecture ★★★★

Author(s): Kelly; Ulam

The deck of a graph $ G $ is the multiset consisting of all unlabelled subgraphs obtained from $ G $ by deleting a vertex in all possible ways (counted according to multiplicity).

Conjecture   If two graphs on $ \ge 3 $ vertices have the same deck, then they are isomorphic.

Keywords: reconstruction

Sums of independent random variables with unbounded variance ★★

Author(s): Feige

Conjecture   If $ X_1, \dotsc, X_n \geq 0 $ are independent random variables with $ \mathbb{E}[X_i] \leq \mu $, then $$\mathrm{Pr} \left( \sum X_i - \mathbb{E} \left[ \sum X_i \right ] < \delta \mu \right) \geq \min \left ( (1 + \delta)^{-1} \delta, e^{-1} \right).$$

Keywords: Inequality; Probability Theory; randomness in TCS

Dragon Ball Legends Cheats Generator (Ios Android) ★★

Author(s):

Dragon Ball Legends Cheats Generator (Ios Android)

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Seagull problem ★★★

Author(s): Seymour

Conjecture   Every $ n $ vertex graph with no independent set of size $ 3 $ has a complete graph on $ \ge \frac{n}{2} $ vertices as a minor.

Keywords: coloring; complete graph; minor

Invariant subspace problem ★★★

Author(s):

Problem   Does every bounded linear operator on an infinite-dimensional separable Hilbert space have a non-trivial closed invariant subspace?

Keywords: subspace

New World Of Tanks Blitz Free Gold Credits Cheats 2024 Tested (extra) ★★

Author(s):

New World Of Tanks Blitz Free Gold Credits Cheats 2024 Tested (extra)

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Monochromatic reachability in arc-colored digraphs ★★★

Author(s): Sands; Sauer; Woodrow

Conjecture   For every $ k $, there exists an integer $ f(k) $ such that if $ D $ is a digraph whose arcs are colored with $ k $ colors, then $ D $ has a $ S $ set which is the union of $ f(k) $ stables sets so that every vertex has a monochromatic path to some vertex in $ S $.

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War Thunder Unlimited Golden Eagles Cheats Generator 2024 (fresh strategy) ★★

Author(s):

War Thunder Unlimited Golden Eagles Cheats Generator 2024 (fresh strategy)

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Cookie Run Kingdom Cheats Generator Android Ios 2024 Cheats Generator (free) ★★

Author(s):

Cookie Run Kingdom Cheats Generator Android Ios 2024 Cheats Generator (free)

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Nearly spanning regular subgraphs ★★★

Author(s): Alon; Mubayi

Conjecture   For every $ \epsilon > 0 $ and every positive integer $ k $, there exists $ r_0 = r_0(\epsilon,k) $ so that every simple $ r $-regular graph $ G $ with $ r \ge r_0 $ has a $ k $-regular subgraph $ H $ with $ |V(H)| \ge (1- \epsilon) |V(G)| $.

Keywords: regular; subgraph

Colouring the square of a planar graph ★★

Author(s): Wegner

Conjecture   Let $ G $ be a planar graph of maximum degree $ \Delta $. The chromatic number of its square is
    \item at most $ 7 $ if $ \Delta =3 $, \item at most $ \Delta+5 $ if $ 4\leq\Delta\leq 7 $, \item at most $ \left\lfloor\frac32\,\Delta\right\rfloor+1 $ if $ \Delta\ge8 $.

Keywords:

Nowhere-zero flows ★★

Author(s):

Nowhere-zero flows

Keywords:

Rainbow Six Siege Cheats Generator Latest Version 2024 New Cheats Generator (Unique) ★★

Author(s):

Rainbow Six Siege Cheats Generator Latest Version 2024 New Cheats Generator (Unique)

Keywords: