Semantic Role Labeling (SRL) determines the relationship between a given sentence and a predicate, such as a verb. Sometimes, the inference is provided as a question. An example of a role might be: where or when did something happen? The following is a visualization from http://demo.allennlp.org/semantic-role-labeling:

The preceding visualization shows semantic labeling, which created semantic associations between the different pieces of text, such as The keys being needed for the purpose to access the building. The reader may experiment with different examples using the URL link provided earlier.