5 The following equation summarises the tree edit distance measure: The possible values of this metric are non-negative real numbers.
the common criteria are based on the typology of word order (Naseem et al., 2012;täckström et al., 2013;Zhang and Barzilay, 2015) or part-of-speech n-grams (Rosa and Zabokrtsky, 2015;Agić, 2017).