A <a href="https://en.wikipedia.org/wiki/Partially_ordered_set" class="extiw" title="en:Partially ordered set">partially ordered set</a> in which the bounds of the <a href="https://en.wikipedia.org/wiki/1/3%E2%80%932/3_conjecture" class="extiw" title="en:1/3–2/3 conjecture">1/3–2/3 conjecture</a> are exactly met, factored as a <a href="https://en.wikipedia.org/wiki/Series-parallel_partial_order" class="extiw" title="en:Series-parallel partial order">series composition</a> of 1-element and 3-element partial orders. According to a result of Aigner ("A note on merging", <i>Order</i> <b>2</b> (1985) 257–264, <a href="//doi.org/10.1007/BF00333131" class="extiw" title="doi:10.1007/BF00333131">doi:10.1007/BF00333131</a>) this is the only extreme case for width-two partial orders.
<a href="//commons.wikimedia.org/wiki/User:David_Eppstein" class="mw-redirect" title="User:David Eppstein">David Eppstein</a>
<span class="int-own-work" lang="en">Own work</span>