F-measure

In the UNL System, the F-measure (or F1-score) is the measure of a grammar's accuracy. It considers both the precision and the recall of the grammar to compute the score, according to the formula

F-measure = 2 x ( (precision x recall) / (precision + recall) )

In the above:

• precision is the number of correct results divided by the number of all returned results
• recall is the number of correct results divided by the number of results that should have been returned

A result is considered "returned" in the following cases:

• In UNLization, when the output is a graph (i.e., all the nodes are interlinked) made only of UW's (i.e., without natural language words)
• In NLization, when the output is a list of natural language words (i.e., without any UW).

A result is considered "correct" when the Levensthein distance between the actual result and the expected result was less than 30% of the length of the expected result. The Levenshtein distance is defined as the minimal number of characters you have to replace, insert or delete to transform a string (the actual output) into another one (the expected output).