<ul>
<?php  
$exclude_id = $post->ID; 
$posttags = get_the_tags(); 
$i = 0;
$limit = 4 ;
if ( $posttags ) { 
	$tags = ''; foreach ( $posttags as $tag ) $tags .= $tag->name . ',';
	$args = array(
		'post_status' => 'publish',
		'tag_slug__in' => explode(',', $tags), 
		'post__not_in' => explode(',', $exclude_id), 
		'caller_get_posts' => 1, 
		'orderby' => 'comment_date', 
		'posts_per_page' => $limit
	);
	query_posts($args); 
	while( have_posts() ) { the_post();
		echo '<li><a href="'.get_permalink().'">', deel_thumbnail(), '<br>', get_the_title(), '</a></li>';
		$exclude_id .= ',' . $post->ID; $i ++;
	};
	wp_reset_query();
}
if ( $i < $limit ) { 
	$cats = ''; foreach ( get_the_category() as $cat ) $cats .= $cat->cat_ID . ',';
	$args = array(
		'category__in' => explode(',', $cats), 
		'post__not_in' => explode(',', $exclude_id),
		'caller_get_posts' => 1,
		'orderby' => 'comment_date',
		'posts_per_page' => $limit - $i
	);
	query_posts($args);
	while( have_posts() ) { the_post();
		echo '<li><a href="'.get_permalink().'">', deel_thumbnail(), '<br><p>', get_the_title(), '</p></a></li>';
		$i ++;
	};
	wp_reset_query();
}
if ( $i  == 0 ){
	echo '<li>暂无相关文章！</li>';
}
?>
</ul>