$re = '/^(\{(\(\d,\d\),)*\(\d,\d\)\}),(?1)$/m';
$str = '{(1,4)(2,3),(3,8),(6,7)},{(1,8),(2,7),(3,6),(4,5)}
{(1,4),(2,3),(3,8),(6,7)},{(1,8),(2,7),(3,6),(4,5)}
{(1,4),(2,3),(3,8),(6,7)},{(1,8),(2,7),(3,6),(4,5)},';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php