Task	Model	Language	N-gram-based	Embedding-based	Diversity	Ours
BLEU	ROUGE-L	METEOR	BERTScore	Distinct-1	Distinct-2	Ensemble
SG	M-BERT	fr->en	2.62	18.8	0.102	0.893	0.907	0.986	31.131
fr->de	2.47	14.1	0.134	0.721	0.948	0.995	34.44
fr->es	1.66	12.6	0.11	0.72	0.944	0.994	30.191
fr->zh	4.83	24.6	-	0.659	0.996	0.42	26.564
XLM	fr->en	3.19	19.6	0.102	0.895	0.961	0.993	32.028
fr->de	3.21	25.7	0.141	0.729	0.958	0.99	29.395
fr->es	3.17	24.9	0.129	0.737	0.964	0.991	28.116
fr->zh	5.49	25.9	-	0.666	0.986	0.471	26.284
mBART	fr->en	1.83	18	0.085	0.892	0.953	0.983	32.32
fr->de	1.65	12.6	0.117	0.724	0.97	0.997	33.679
fr->es	0.97	9.3	0.085	0.713	0.898	0.962	29.546
fr->zh	6.07	26.9	-	0.672	0.996	0.346	26.474
mT5	fr->en	3.4	20.1	0.104	0.901	0.968	0.994	32.827
fr->de	3.22	14.8	0.14	0.731	0.97	0.99	34.333
fr->es	2.9	14.7	0.128	0.741	0.966	0.989	32.558
fr->zh	5.64	27.2	-	0.674	0.997	0.266	26.986
OG	M-BERT	fr->en	8.47	34.3	0.163	0.888	0.867	0.978	29.537
fr->de	5.29	21	0.185	0.735	0.903	0.984	31.182
fr->es	5.41	20.9	0.286	0.789	0.911	0.987	31.429
fr->zh	7.67	28.9	-	0.683	0.997	0.926	26.186
XLM	fr->en	13.53	39.5	0.197	0.907	0.955	0.994	31.174
fr->de	8.5	35.1	0.234	0.771	0.973	0.998	29.541
fr->es	15.76	45.6	0.359	0.827	0.953	0.996	28.703
fr->zh	15.01	36.5	-	0.726	0.996	0.998	28.297
mBART	fr->en	5.4	31.6	0.128	0.892	0.981	0.999	29.219
fr->de	4	21	0.164	0.744	0.981	0.998	31.385
fr->es	11.74	31.1	0.328	0.825	0.973	0.999	33.473
fr->zh	7.32	30	-	0.673	0.993	0.989	24.29
mT5	fr->en	13.07	40.7	0.196	0.911	0.97	0.998	32.631
fr->de	8.53	26.2	0.224	0.774	0.983	0.999	33.533
fr->es	14.74	34.3	0.363	0.834	0.965	0.997	34.057
fr->zh	13.11	35.5	-	0.723	0.997	0.997	27.876
TG	M-BERT	fr->en	10.46	32.4	0.176	0.885	0.965	0.998	30.775
fr->de	6.11	16.7	0.166	0.715	0.949	0.997	31.288
fr->es	8.3	25.6	0.265	0.754	0.921	0.996	29.096
fr->zh	9.98	27.2	-	0.672	0.989	0.503	26.035
XLM	fr->en	11.64	31.2	0.188	0.884	0.964	0.995	29.661
fr->de	7.51	21.8	0.196	0.72	0.956	0.996	30.472
fr->es	10.99	29.3	0.288	0.757	0.911	0.993	28.422
fr->zh	14.25	28.1	-	0.684	0.978	0.613	27.015
mBART	fr->en	1.95	21.4	0.079	0.847	0.878	0.946	23.241
fr->de	1.49	11.5	0.088	0.663	0.838	0.925	26.812
fr->es	1.35	15.7	0.131	0.689	0.844	0.932	22.517
fr->zh	1.7	12.1	-	0.542	0.836	0.432	17.833
mT5	fr->en	12.13	32.9	0.188	0.891	0.973	0.996	31.065
fr->de	8.03	19.7	0.196	0.723	0.957	0.994	31.076
fr->es	12.04	28.6	0.298	0.762	0.911	0.993	30.165
fr->zh	12.1	26.8	-	0.675	0.969	0.67	26.812
Summ	M-BERT	fr->en	11.19	36.4	0.16	0.869	0.815	0.986	21.222
fr->de	7.16	24.8	0.195	0.716	0.813	0.986	26.214
fr->es	9.07	31.7	0.264	0.742	0.762	0.98	20.92
fr->zh	12.45	37.1	-	0.698	0.855	0.916	19.512
XLM	fr->en	11.82	36.3	0.176	0.876	0.766	0.956	22.262
fr->de	7.52	29.9	0.19	0.716	0.796	0.951	21.358
fr->es	10.89	35.5	0.276	0.747	0.732	0.95	20.133
fr->zh	13.3	37.7	-	0.702	0.842	0.927	18.906
mBART	fr->en	12.97	38	0.171	0.873	0.844	0.993	21.336
fr->de	6.75	25.1	0.186	0.704	0.801	0.98	24.534
fr->es	10.61	32.5	0.271	0.737	0.749	0.982	20.158
fr->zh	10.46	34.1	-	0.684	0.874	0.967	19.532
mT5	fr->en	6	31.4	0.118	0.872	0.847	0.964	22.804
fr->de	3.43	21.4	0.127	0.696	0.824	0.937	22.566
fr->es	5.1	28.2	0.209	0.729	0.792	0.951	19.37
fr->zh	7.74	31.3	-	0.68	0.889	0.958	21.627