We establish an optimal upper bound (negative result) of $\sim 0.526$ on the competitive ratio of the fractional version of online bipartite matching with two-sided vertex arrivals, matching the lower bound (positive result) achieved by Wang and Wong (ICALP 2015), and Tang and Zhang (EC 2024).

翻译：我们针对顶点双边到达的在线二分图匹配分数版本，建立了竞争比的最优上界（负面结果）为 $\sim 0.526$，该结果与 Wang 和 Wong（ICALP 2015）以及 Tang 和 Zhang（EC 2024）所达成的下界（正面结果）相匹配。