A speaker's level of formality can reveal information about their familiarity with a person, opinions of a topic, and goals for an interaction (Hovy, 1987;Endrass et al., 2011).
the ability to recognize formality is an integral part of dialogue systems (Mairesse, 2008;Mairesse and Walker, 2011;Battaglino and Bickmore, 2015), sociolinguistic analyses (Danescu-Niculescu-Mizil et al., 2012;Justo et al., 2014;Krishnan and Eisenstein, 2015), human-computer interaction (Johnson et al., 2005;Khosmood and Walker, 2010), summarization (Sidhaye and Cheung, 2015), and automatic writing assessment (Felice and Deane, 2012).