Prove that $\forall n\in\mathbb{Z}^+_0:(\exists b\in\mathbb{Z}^+_0:(\forall m\in\mathbb{Z}^+_0:((\exists x\in\mathbb{Z}^+_0:(x+m = b))\lor(\exists s\in\mathbb{Z}^+_0:(\exists p\in\mathbb{Z}^+_0:((\neg(\exists x\in\mathbb{Z}^+_0:(p+x = 1)))\land(\neg(\exists x\in\mathbb{Z}^+_0:(\exists y\in\mathbb{Z}^+_0:(p = (x+2) \cdot (y+2)))))\land(\exists x\in\mathbb{Z}^+_0:(p = m+x+1))\land(\exists r\in\mathbb{Z}^+_0:((\forall x\in\mathbb{Z}^+_0:(\forall y\in\mathbb{Z}^+_0:((\neg(x \cdot y = r))\lor(x = 1)\lor(\exists z\in\mathbb{Z}^+_0:(x = z \cdot p)))))\land(\exists x\in\mathbb{Z}^+_0:(\exists y\in\mathbb{Z}^+_0:((\exists z\in\mathbb{Z}^+_0:(r = y+z+1))\land(s = r \cdot (p \cdot x + m) + y))))))\land(\forall u\in\mathbb{Z}^+_0:((\exists x\in\mathbb{Z}^+_0:(u = p+x))\lor(u = 0)\lor(u = n+1)\lor(\neg(\exists r\in\mathbb{Z}^+_0:((\forall x\in\mathbb{Z}^+_0:(\forall y\in\mathbb{Z}^+_0:((\neg(x \cdot y = r))\lor(x = 1)\lor(\exists z\in\mathbb{Z}^+_0:(x = z \cdot p)))))\land(\exists x\in\mathbb{Z}^+_0:(\exists y\in\mathbb{Z}^+_0:((\exists z\in\mathbb{Z}^+_0:(r = y+z+1))\land(s = r \cdot (p \cdot x + u) + y)))))))\lor(\exists v\in\mathbb{Z}^+_0:(\exists k\in\mathbb{Z}^+_0:((\neg(v = 0))\land((u = v \cdot (k+2))\lor(u = v \cdot (k+2) + 1))\land(\exists r\in\mathbb{Z}^+_0:((\forall x\in\mathbb{Z}^+_0:(\forall y\in\mathbb{Z}^+_0:((\neg(x \cdot y = r))\lor(x = 1)\lor(\exists z\in\mathbb{Z}^+_0:(x = z \cdot p)))))\land(\exists x\in\mathbb{Z}^+_0:(\exists y\in\mathbb{Z}^+_0:((\exists z\in\mathbb{Z}^+_0:(r = y+z+1))\land(s = r \cdot (p \cdot x + v) + y)))))))))))))))))$. Proposed by Warren Bei
Problem
Source: 2024 RELSMO 7
Tags: algebra, logic
28.06.2024 06:46
bro what i gave up trying to understand it after the first line my guess is once you decode it, it's probably something simple to prove
28.06.2024 06:51
not the 17 consecutive right parentheses at the end
28.06.2024 07:16
This is like at least 2 MOHS
28.06.2024 08:33
This is equivalent to the following problem. Quote: Consider the directed graph with vertices $\mathbb{N}$ and edges $m\to km$ and $m\to km+1$, for $m,k\in \mathbb{N}$ and $k\geq 2$. Then, starting from any positive integer $n$, one can reach every sufficiently large integer via a directed path. I was told this is apparently open. So we prove a weaker version of the problem, that we can reach almost every number. Theorem. Fix a positive integer $n$, and let $f(N)$ denote the number of positive integers $m\leq N$ reachable from $n$. Then $f(N)/N\to 1$ as $N\to\infty$. Proof. We can reach any number of the form $kn+1$ from $n$, for $k\geq 2$. In particular, we can reach a prime number by Dirichlet's theorem, so WLOG assume that $n$ is prime. For a positive integer $m=p_1^{a_1}\cdots p_k^{a_k}$, denote by $\Omega(m):=a_1+\cdots+a_k$. We claim that if $\Omega(m)> 2n$, then $m$ is reachable. If $n\mid m$, then $m$ is reachable, so assume that $n\nmid m$. Suppose $\Omega(m)=r>2n$, then there are distinct positive integers $1<q_1\mid q_2\mid\cdots \mid q_r=m$. By pigeonhole and $r>2n$, there exists $i<j<k$ such that $q_i\equiv q_j\equiv q_k\pmod{n}$, so $q_k/q_i\equiv 1\pmod{n}$ and $q_k/q_i>n+1$. Therefore, $q_k/q_i=\frac{q_k/q_i-1}{n}n+1$ is reachable, thus $m$ is reachable since it is a multiple of $q_k/q_i$. Finally, by the Hardy–Ramanujan theorem, almost all numbers $m$ have approximately $\log\log m$ distinct prime factors. In particular, almost all numbers have more than $2n$ prime factors, so by our claim they are reachable. $\square$