Evaluation:

Table 3 shows the result for several values of the principal parameters. The baseline, (assign an element its most frequent category: O, I-NP or B-NP) provides an F1-score of 80.13. These results were obtained without using lexicalized information (W feature in the example Figure 1).

Table 3: Influence of some parameters.

$\theta$	0.9	0.85	0.80	0.75	0.75	0.5	0.5
length of the context	2	2	2	2	1	2	1
nb rules	1144	930	884	811	361	1122	592
nb exceptions	192	230	287	297	134	669	357
F w/o excep	88.79	90.19	89.12	89.28	88.08	88.21	87.61
F with excep	88.93	90.31	90.47	90.62	89.26	90.70	90.07