<p>After some discussion in the comments above, the emerging consensus seems to be:</p>

<ol>
<li>Map <a href="https://stats.stackexchange.com/questions/tagged/gradient-boosted-trees" class="post-tag" title="show questions tagged &#39;gradient-boosted-trees&#39;" rel="tag">gradient-boosted-trees</a> and <a href="https://stats.stackexchange.com/questions/tagged/gbm" class="post-tag" title="show questions tagged &#39;gbm&#39;" rel="tag">gbm</a> to <a href="https://stats.stackexchange.com/questions/tagged/boosting" class="post-tag" title="show questions tagged &#39;boosting&#39;" rel="tag">boosting</a> as synonyms.</li>
<li>Leave <a href="https://stats.stackexchange.com/questions/tagged/adaboost" class="post-tag" title="show questions tagged &#39;adaboost&#39;" rel="tag">adaboost</a> and <a href="https://stats.stackexchange.com/questions/tagged/xgboost" class="post-tag" title="show questions tagged &#39;xgboost&#39;" rel="tag">xgboost</a> alone.</li>
</ol>

<p>This plan looks good to me. Upvote if agree, downvote (and explain in the comments!) if disagree.</p>

<p><strong>Update (Nov 5): This has been implemented.</strong></p>
