tyle="">a</span><span class="mord mathnormal mtight" style="">t</span><span class="mord mathnormal mtight" style="">a</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.15122857142857138em;"><span></span></span></span></span></span></span></span><span class="mopen mtight" style="">(</span><span class="mord mtight" style=""><span class="mord mtight coloredeq eqn" style=""><span class="mord vbox mtight" style=""><span class="thinb