<?
function singplural($string){ 
$string = preg_replace("/[^A-Za-z 0-9]/", "", $string);
$mstring=array(); $string = explode(' ', strtolower(trim($string)));
foreach($string as $key) { $mstring[] =  depluralize($key); $mstring[] =  pluralize($key);}
$mary=array_merge($string,$mstring); $mary=array_unique($mary);
foreach($mary as $keywords) { $mkeywords .= ' '.$keywords; }
return $mkeywords;
}
function pluralize($word){
    $rules = array( 	'o' => 'os', 	'oy' => 'oys',  'y' => 'ies', 	'x' => 'xes', 	'oe' => 'oes',  	'x' => 'xes', 	'h' => 'hes', 	'ss' => 'sses', 		'se' => 'ses', 	'ch' => 'ches', 	'es' => 'es');
    foreach(array_keys($rules) as $key){
        if(substr($word, (strlen($key) * -1)) != $key) 
            continue;
        if($key === false) 
            return $word;
        return substr($word, 0, strlen($word) - strlen($key)) . $rules[$key]; 
    }
    return $word.'s';
}
function depluralize($word){
    $rules = array( 	'ss' => 'ss', 	'os' => 'o', 	'ys' => 'y', 'ies' => 'y', 	'xes' => 'x', 	'oes' => 'o',  	'xes' => 'x', 	'hes' => 'h', 	'sses' => 'ss', 		'ses' => 'se', 	'ches' => 'ch', 		's' => '');
    foreach(array_keys($rules) as $key){
        if(substr($word, (strlen($key) * -1)) != $key) 
            continue;
        if($key === false) 
            return $word;
        return substr($word, 0, strlen($word) - strlen($key)) . $rules[$key]; 
    }
    return $word;
}
?>