pan name="first">first: <span name="provingground.translation.TermRec.U" class="extype">U</span></span>, <span name="second">second: <span name="provingground.translation.TermRec.U" class="extype">U</span></span>)</span><span class="result">: <span name="provingground.translation.TermRec.U" class="extype">U</span></span></span></li><li class="indented0 " name="provingground.translation.TermRec#sigma" group="Ungrouped" fullComment="no" data-isabs="true" visbl="pub"><a id="sigma(fibre:U):U"></a><a id="sigma(U