我也有同样的想法，并编写了一个小插件来帮助我做到这一点。

function get_pew_related_data($args, $post_id, $related_id) {
    global $post, $wpdb;
    $post_id = intval( $post_id );
    if( !$post_id && $post->ID ) {
        $post_id = $post->ID;
    }

    if( !$post_id ) {
        return false;
    }

    $defaults = array(
        \'taxonomy\' => \'topics\',
        \'post_type\' => array(\'post\'),
        \'max\' => 5
    );
    $options = wp_parse_args( $args, $defaults );

    $transient_name = \'pew-related-\' . $options[\'taxonomy\'] . \'-\' . $post_id;

    if( isset($_GET[\'flush-related-links\']) && is_user_logged_in() ) {
        echo \'<p>Related links flushed! (\' . $transient_name . \')</p>\';
        delete_transient( $transient_name );
    }

    $output = get_transient( $transient_name );
    if( $output !== false && !is_preview() ) {
        //echo $transient_name . \' read!\';
        return $output;
    } 

    $args = array(
        \'fields\' => \'ids\',
        \'orderby\' => \'count\',
        \'order\' => \'ASC\'
    );
    $orig_terms_set = wp_get_object_terms( $post_id, $options[\'taxonomy\'], $args );

    //Make sure each returned term id to be an integer.
    $orig_terms_set = array_map(\'intval\', $orig_terms_set);

    //Store a copy that we\'ll be reducing by one item for each iteration. 
    $terms_to_iterate = $orig_terms_set;

    $post_args = array(
        \'fields\' => \'ids\',
        \'post_type\' => $options[\'post_type\'],
        \'post__not_in\' => array($post_id),
        \'posts_per_page\' => 50
    );
    $output = array();
    while( count( $terms_to_iterate ) > 1 ) {

        $post_args[\'tax_query\'] = array(
            array(
                \'taxonomy\' => $options[\'taxonomy\'],
                \'field\' => \'id\',
                \'terms\' => $terms_to_iterate,
                \'operator\' => \'AND\'
            )
        );

        $posts = get_posts( $post_args );

        /*
        echo \'<br>\';
        echo \'<br>\';
        echo $wpdb->last_query;
        echo \'<br>\';
        echo \'Terms: \' . implode(\', \', $terms_to_iterate);
        echo \'<br>\';
        echo \'Posts: \';
        echo \'<br>\';
        print_r( $posts );
        echo \'<br>\';
        echo \'<br>\';
        echo \'<br>\';
        */

        foreach( $posts as $id ) {
            $id = intval( $id );
            if( !in_array( $id, $output) ) {
                $output[] = $id;
            }
        }
        array_pop( $terms_to_iterate );
    }

    $post_args[\'posts_per_page\'] = 10;
    $post_args[\'tax_query\'] = array(
        array(
            \'taxonomy\' => $options[\'taxonomy\'],
            \'field\' => \'id\',
            \'terms\' => $orig_terms_set
        )
    );

    $posts = get_posts( $post_args );

    foreach( $posts as $count => $id ) {
        $id = intval( $id );
        if( !in_array( $id, $output) ) {
            $output[] = $id;
        }
        if( count($output) > $options[\'max\'] ) {
            //We have enough related post IDs now, stop the loop.
            break;
        }
    }

    if( !is_preview() ) {
        //echo $transient_name . \' set!\';
        set_transient( $transient_name, $output, 24 * HOUR_IN_SECONDS );
    }

    return $output;
}

function pew_related( $args = array(), $post_id = \'\', $related_id = \'\' ) {
    $post_ids = get_pew_related_data( $args, $post_id, $related_id );

    if( !$post_ids ) {
        return false;
    }

    $defaults = array(
        \'post__in\' => $post_ids,
        \'orderby\' => \'post__in\',
        \'post_type\' => array(\'post\'),
        \'posts_per_page\' => min( array(count($post_ids), 10)),
        \'related_title\' => \'Related Posts\'
    );
    $options = wp_parse_args( $args, $defaults );

    $related_posts = new WP_Query( $options );
    if( $related_posts->have_posts() ):
    ?>
    <h5><?=$options[\'related_title\']?></h5>
    <div id="related-material" class="promo">
        <?php while ( $related_posts->have_posts() ):
            $related_posts->the_post();
        ?>
            <a class="post" href="<?=the_permalink();?>">
                <div class="meta">
                    <?php
                    $post_project = wp_get_object_terms($related_posts->post->ID, \'projects\');
                    $project = \'Pew Research Center\';
                    $project_slug = \'\';
                    if( isset($post_project[0]) ) {
                        $project = $post_project[0]->name;
                        $project_slug =  $post_project[0]->slug;
                    } elseif( $related_posts->post->post_type == \'fact-tank\' ) {
                        $project = \'Fact Tank\';
                        $project_slug = \'fact-tank\';
                    }
                    ?>
                    <span class="project <?=$project_slug;?> right-seperator"><?=$project;?></span>
                    <span class="date"><?php the_time(\'M j, Y\'); ?></span>
                </div>
                <h2><?=the_title();?></h2>
            </a>
        <?php endwhile;
            wp_reset_postdata();

         ?> 
    </ol>
    </div>
    <?php
    endif;

}

算法的工作原理如下：

从帖子中按count升序（从最不受欢迎到最受欢迎）获取所有术语，循环查看这组术语，并查找包含Term1、Term2和Term3的帖子。每次迭代都会从列表中删除最不受欢迎的术语，扩大结果，直到我们获得所需的帖子数量，或者我们只剩下一个术语要检查