Editing Probabilistic context-free grammar (section)

===== Assign production probabilities to each rule in the grammar =====
Each structure in the grammar is assigned production probabilities devised from the structures of the training dataset. These prior probabilities give weight to predictions accuracy.<ref name="Knudsen 1999" /><ref name="Lari and Young 1990" /><ref name="Lari and Young 1991" /> The number of times each rule is used depends on the observations from the training dataset for that particular grammar feature. These probabilities are written in parentheses in the grammar formalism and each rule will have a total of 100%.<ref name="Knudsen 2003" /> For instance:

:              <math> S \to LS (80\%) |L (20\%)</math>
:              <math>L \to s (70\%) | dFd (30\%)</math>
:              <math>F \to dFd (60.4\%)| LS (39.6\%)</math>