External links
- Rhetorical Structure Theory — RST website, created by William C. Mann, maintained by Maite Taboada
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A discourse relation (also coherence relation or rhetorical relation) is a description of how two segments of discourse are logically and/or structurally connected to one another.
A widely upheld position is that in coherent discourse, every individual utterance is connected by a discourse relation with a context element, e.g., another segment that corresponds to one or more utterances. An alternative view is that discourse relations correspond to the sense (semantic meaning or pragmatic function) of discourse connectives (discourse markers, discourse cues, e.g., conjunctions, certain adverbs), so that every discourse connective elicits at least one discourse relation. Both views converge to some extent in that the same underlying inventory of discourse relations is assumed.
There is no general agreement on the exact inventory of discourse relations, but current inventories are specific to theories or frameworks. With ISO/TS 24617-5 (Semantic annotation framework; Part 5: Discourse structure, SemAF-DS), [1] a standard has been proposed, but it is not widely used in existing annotations or by tools. Yet another proposal to derive at a generalized discourse relation inventory is the cognitive approach to coherence relations (CCR), which reduces discourse relations to a combination of five parameters. [2]
In addition to a discourse relation inventory, some (but not all) theories postulate structural constraints on discourse relations, and if paratactic (coordinate) or hypotactic (subordinate) relations are distinguished that hold across two or more text spans, coherence in discourse can be modelled as a tree (as in RST, see below) or over a tree (as in SDRT, see below). [3]
In a series of seminal papers, Jerry Hobbs [4] [5] investigated the interplay of discourse relations and coherence since the late 1970s. His work has been the basis for most subsequent theories and annotation frameworks of discourse relations.
He proposed the following relations: [6]
Introduced in 1987, Rhetorical Structure Theory (RST) [7] uses rhetorical relations as a systematic way for an analyst to annotate a given text. An analysis is usually built by reading the text and constructing a tree using the relations. RST has been designed as a framework for the principled annotation discourse, driven by theoretical considerations, but with an applied perspective.
There is some variation among RST relations in different applications and annotated corpora, but the core inventory formulated by Mann and Thompson (1987) is generally considered as the basis. [7]
In its original motivation, SDRT attempts to complement Discourse Representation Theory (DRT) with RST-style discourse relations. Asher and Lascarides (2003) categorize SDRT discourse relations into several classes:
Metatalk relations include:
In the early days of computational discourse, the study of discourse relations was closely entangled with the study of discourse structure, so that theories such as RST and SDRT effectively postulate tree structures. (SDRT permits relations between independent nodes in a tree, but the tree still defines accessibility domains.) For practical annotation, however, this was felt to be a disadvantage because discourse relations could only be annotated after the global coherence of a particular text has been understood, and annotators disagreed widely (as already observed by Mann and Thompson 1987). [7] For theoretical reasons, the tree model was criticized because at least some types of discourse relations (especially what Hobbs referred to as elaboration) was apparently not constrained by tree structures but could connect elements disconnected in the tree (Knott et al. 2001). [9]
This has been the motivation to perform the annotation of discourse relations independently from discourse structure, and this "shallow" model of discourse coherence could be annotated from local context alone. The most prominent of these models has been the Penn Discourse Treebank (PDTB). [10] PDTB is focusing on the annotation of discourse cues (discourse markers, discourse connectives), which are assigned an internal argument (to which the discourse marker is attached), an external argument (target or attachment point of the relation) and a sense (discourse relation). Both arguments are defined as the smallest string that expresses the meaning of the utterances to be connected. Unlike RST and SDRT, PDTB does not postulate any structural constraints on discourse relations, but only defines a limit for the search space for a possible external argument. Starting with PDTB v.2.0, also implicit cues have been annotated, i.e., for utterances without discourse markers, annotators were asked to decide whether and which known discourse cue could be inserted and what its form, arguments and discourse relation would be.
In practice, PDTB is widely used for creating discourse resources. In comparison to RST and SDRT, it provides less information.
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In physics, specifically in quantum mechanics, a coherent state is the specific quantum state of the quantum harmonic oscillator, often described as a state which has dynamics most closely resembling the oscillatory behavior of a classical harmonic oscillator. It was the first example of quantum dynamics when Erwin Schrödinger derived it in 1926, while searching for solutions of the Schrödinger equation that satisfy the correspondence principle. The quantum harmonic oscillator arise in the quantum theory of a wide range of physical systems. For instance, a coherent state describes the oscillating motion of a particle confined in a quadratic potential well. The coherent state describes a state in a system for which the ground-state wavepacket is displaced from the origin of the system. This state can be related to classical solutions by a particle oscillating with an amplitude equivalent to the displacement.
In the philosophy of language and speech acts theory, performative utterances are sentences which not only describe a given reality, but also change the social reality they are describing.
In proof theory, a coherent space is a concept introduced in the semantic study of linear logic.
In linguistics, focus is a grammatical category that conveys which part of the sentence contributes new, non-derivable, or contrastive information. In the English sentence "Mary only insulted BILL", focus is expressed prosodically by a pitch accent on "Bill" which identifies him as the only person Mary insulted. By contrast, in the sentence "Mary only INSULTED Bill", the verb "insult" is focused and thus expresses that Mary performed no other actions towards Bill. Focus is a cross-linguistic phenomenon and a major topic in linguistics. Research on focus spans numerous subfields including phonetics, syntax, semantics, pragmatics, and sociolinguistics.
In generative grammar, non-configurational languages are languages characterized by a flat phrase structure, which allows syntactically discontinuous expressions, and a relatively free word order.
In generative grammar and related frameworks, a node in a parse tree c-commands its sister node and all of its sister's descendants. In these frameworks, c-command plays a central role in defining and constraining operations such as syntactic movement, binding, and scope. Tanya Reinhart introduced c-command in 1976 as a key component of her theory of anaphora. The term is short for "constituent command".
In linguistics, a treebank is a parsed text corpus that annotates syntactic or semantic sentence structure. The construction of parsed corpora in the early 1990s revolutionized computational linguistics, which benefitted from large-scale empirical data.
Rhetoric of science is a body of scholarly literature exploring the notion that the practice of science is a rhetorical activity. It emerged following a number of similarly-oriented disciplines during the late 20th century, including the disciplines of sociology of scientific knowledge, history of science, and philosophy of science, but it is practiced most fully by rhetoricians in departments of English, speech, and communication.
Linguistic categories include
Glue semantics, or simply Glue, is a linguistic theory of semantic composition and the syntax–semantics interface which assumes that meaning composition is constrained by a set of instructions stated within a formal logic. These instructions, called meaning constructors, state how the meanings of the parts of a sentence can be combined to provide the meaning of the sentence.
Merge is one of the basic operations in the Minimalist Program, a leading approach to generative syntax, when two syntactic objects are combined to form a new syntactic unit. Merge also has the property of recursion in that it may apply to its own output: the objects combined by Merge are either lexical items or sets that were themselves formed by Merge. This recursive property of Merge has been claimed to be a fundamental characteristic that distinguishes language from other cognitive faculties. As Noam Chomsky (1999) puts it, Merge is "an indispensable operation of a recursive system ... which takes two syntactic objects A and B and forms the new object G={A,B}" (p. 2).
Genre criticism, a method within rhetorical criticism, analyzes texts in terms of their genre: the set of generic expectations, conventions, and constraints that guide their production and interpretation. In rhetoric, the theory of genre provides a means to classify and compare artifacts in terms of their formal, substantive and contextual features. By grouping artifacts with others which have similar formal features or rhetorical exigencies, rhetorical critics can shed light on how authors use or flout conventions for their own purposes. Genre criticism has thus become one of the main methodologies within rhetorical criticism.
Meaning–text theory (MTT) is a theoretical linguistic framework, first put forward in Moscow by Aleksandr Žolkovskij and Igor Mel’čuk, for the construction of models of natural language. The theory provides a large and elaborate basis for linguistic description and, due to its formal character, lends itself particularly well to computer applications, including machine translation, phraseology, and lexicography.
Combinatory categorial grammar (CCG) is an efficiently parsable, yet linguistically expressive grammar formalism. It has a transparent interface between surface syntax and underlying semantic representation, including predicate–argument structure, quantification and information structure. The formalism generates constituency-based structures and is therefore a type of phrase structure grammar.
In artificial intelligence and related fields, an argumentation framework is a way to deal with contentious information and draw conclusions from it using formalized arguments.
Rhetorical structure theory (RST) is a theory of text organization that describes relations that hold between parts of text. It was originally developed by William Mann, Sandra Thompson, Christian M.I.M. Matthiessen and others at the University of Southern California's Information Sciences Institute (ISI) and defined in a 1988 paper. The theory was developed as part of studies of computer-based text generation. Natural language researchers later began using RST in text summarization and other applications. It explains coherence by postulating a hierarchical, connected structure of texts. In 2000, Daniel Marcu, also of ISI, demonstrated that practical discourse parsing and text summarization also could be achieved using RST.
William C. "Bill" Mann was a computer scientist and computational linguist, the originator of Rhetorical Structure Theory (RST) and a president of the Association for Computational Linguistics (1987–1988). He is especially well known for his work in text generation.
In linguistics, givenness is a phenomenon in which a speaker assumes that contextual information of a topic of discourse is already known to the listener. The speaker thus considers it unnecessary to supply further contextual information through an expression's linguistic properties, its syntactic form or position, or its patterns of stress and intonation. Givenness involves contextual information in a discourse that is given, or assumed to be known, by the addressee in the moment of utterance. Therefore, a given expression must be known from prior discourse.
Salwa El-Awa is an Egyptian-British linguist and Islamic scholar. She is currently a lecturer of Arabic and Islamic Studies at Swansea University.
In formal semantics, the squiggle operator is an operator which constrains the occurrence of focus. On one common definition, the squiggle operator takes a syntactic argument and a discourse salient argument and introduces a presupposition that the ordinary semantic value of is either a subset or an element of the focus semantic value of . The squiggle was first introduced by Mats Rooth in 1992 as part of his treatment of focus within the framework of alternative semantics. It has become one of the standard tools in formal work on focus, playing a key role in accounts of contrastive focus, ellipsis, deaccenting, and question-answer congruence.