$rqQ=0;$rqE=0;$rqS=0;$hasFrac=0;$hasDD=0;$sample=null;
DB::table('questions')->where('qa_status','ai_generated')->orderBy('id')->chunkById(2000, function($rows) use (&$rqQ,&$rqE,&$hasFrac,&$hasDD,&$sample){
  foreach ($rows as $r) {
    if (strpos((string)$r->question,'\\(')!==false) $rqQ++;
    if (strpos((string)$r->explanation,'\\(')!==false) $rqE++;
    if (strpos((string)$r->question,'$$\\frac')!==false){ $hasFrac++; if(!$sample)$sample=$r; }
    if (strpos((string)$r->question,'$$')!==false) $hasDD++;
  }
});
DB::table('solutions')->where('source','ai')->orderBy('id')->chunkById(2000, function($rows) use (&$rqS){
  foreach ($rows as $r) { if (strpos((string)$r->solution,'\\(')!==false) $rqS++; }
});
echo "literal backslash-paren remaining: Q=$rqQ E=$rqE S=$rqS\n";
echo "questions with \$\$ : $hasDD ; with \$\$\\frac : $hasFrac\n";
if ($sample) echo "sample #".$sample->id.": ".substr(preg_replace('/\s+/',' ',$sample->question),0,160)."\n";