Difference between revisions of "Theory of possible worlds"

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[[IRIS Wiki]] - [[Narrative Theories]] - '''{{PAGENAME}}'''
 
[[IRIS Wiki]] - [[Narrative Theories]] - '''{{PAGENAME}}'''
 
 
===Authors===
 
===Authors===
Umberto Eco
+
Thomas Pavel, Marie-Laure Ryan, among others.
  
 
===Histo-geographical placement===
 
===Histo-geographical placement===
Italy, 1960's
+
Last quarter of the 20th century.
  
 
===Type of story===
 
===Type of story===
The theory is based on written text, but can be extended to other media.
+
All types, including complex stories.
  
 
===Parent Theories===
 
===Parent Theories===
-
+
Theory of Possible Worlds in Analytic Philosophy.
  
 
===Child Theories===
 
===Child Theories===
-
+
 
  
 
===Brief Description===
 
===Brief Description===
According to Umberto Eco, an author-written text is an unfinished work and requires a reader to complete the effort. A text lives for the value added significance introduced by the reader. More specifically, a text is emitted for someone capable of actualising it; i.e., the text needs to be correlated to an accepted code system. The code system in question needs to be part of the reader’s set of competencies, and to achieve a fair match (between intention and result) the author must consider what Eco calls the Ideal Reader.  The author must make a plan for all possible reader interpretations for the Ideal Reader to be able to interpret meaning into the text. More than a set of competencies possessed by a reader, the Ideal Reader is the set of felicity conditions/success conditions that need to be satisfied for a text's potential content to be fully actualised (Eco U., 1965, p.77)
 
  
A text should be represented by a system of nodes, indicating which node requires cooperation from the (ideal) reader (Eco U., 1965, p.84). If, when faced with one such node, the reader experiences divergence between the world of their experience and the world of the text, he may momentarily suspend belief (or disbelief) until the next clue (as to the appropriate interpretation) is presented. The reader has to turn to the linguistic rules and competencies offered by the language of the text and their own mastery of the possible interpretations. By choosing for the reader the author shapes their text and defines more specifically, what/who the Ideal Reader is.
+
Possible worlds constitute a set of narratological theories that describe narrative in terms of several ''worlds''. Each possible world (PW) is a set of elements that constitute a system. Worlds are interconnected to each other by various hierarchical relations (for example an element of a PW, a character, creates another PW by telling a story).  
The language in which the text is written provides (linguistic) rules and expects a certain encyclopedic competency for its interpretation (again the level of mastery of these two desired by the author are what makes the Ideal Reader, ideal).
+
Possible worlds have been formalized in logico-mathematical terms, with the particular goal to formalize the relations between these PWs.
 +
For example, what is the relation between W<sub>0</sub> and W<sub>D</sub>? What is the accessibility between one possible world to the other? What is the logical truth of an element of W<sub>D</sub>? Etc.
  
The following list describes various cooperative passages where the author and the reader accept a common understanding necessary for the message and the interpretation to coincide:
+
Several kinds of PWs can be found in narrative:
 +
* The actual world (noted W<sub>0</sub>), in which the reader reads a book, the movie audience sees a movie and the audience and actors gather inside a theater.
 +
* The fictional or dramatic world (noted W<sub>D</sub>), that is described by the narrative, inhabited by characters, places, objects, and where narrative actions take places.
 +
* Spectators' subworlds, which are worlds that the reader constructs mentally as possible/anticipated worlds. They correspond to inferential walks described by U. Eco in his [[textual cooperation]] theory.
 +
* Characters' subworlds, generated by “world creating” propositions such as wish, hope, or imagine.
 +
* Alternate fictional worlds, which are parallel to W<sub>D</sub>, when the story explicitly tells several variations on a story so that to create several alternate fictional worlds (It's a wonderful Life (F. Capra), Smoking / No Smoking (A. Resnais), etc.).
  
*base dictionary
+
===Relation with Interactive Storytelling===
**what the words imply: positioning. The story landscape drawn by our understanding of the words.
 
*rules of co-reference
 
**subject-verb agreement from sentence to sentence. The link between the second and first sentence exists only in the second, the first does not need to mention something that will be found in the second.
 
*circumstantial and contextual selection
 
**what experiences of the past allow to derive or reinforce an interpretation ("jurisprudence")
 
*rhetorical and stylistic hypercoding or ideological hypercoding
 
*shared scenario inferences
 
*intertextual scenario inferences
 
  
===Relation with Interactive Storytelling===
+
For Interactive Storytelling, formalizing these possible worlds is a natural option. Artificial Intelligence research provides useful tools for that purpose. For example, the Expert System JESS offers the possibility to apply reasoning rules specific to a “world”, called a module. The very principle of planning is an exploration of possible worlds, in order to generate a solution (in W<sub>D</sub>) that satisfies some given constraints (such as enabling to reach a certain story goal). This relationship is well established in the book from Marie-Laure Ryan's research (Ryan, 1991). In agent-based planning, the plan explore character's subworlds.
In interactive narrative, recognising moments of (possible) divergence and the different types of "clues" that can be offered to the reader can provide an appropriate framework for where to provide a reader with options and indicate on what level (and in what direction) the different options will take the story.
+
However, despite this strong relation between the theory of possible worlds and Artificial Intelligence, current AI algorithms make limited use of the possible worlds they generate. Generated possible worlds reman internal to the algorithms. What is being shown is a single world, W<sub>D</sub>, the best world according to the exploration of other possible worlds. For example, a character, based on possible world's exploration, could say: "If we let it in, the ship could be infected." (Alien movie, R. Scott); or "I you tell her the truth, she will be made at you and tell everything to your boss".
Depending on a reader's interpretation, potential outcomes vary. As a linear story unfolds the room for interpretation on the reader's behalf needs to narrow to successfully capt the author's intended message. In IS, these possible interpretations could be used as eventual story paths. Understanding where the reader's interpretation and the author's intention can deviate, opens the way to provide alternate story paths.  
+
Beyond planning mechanisms, the very fact that a single story can embed a multitude of possible worlds of different natures, each these subworlds being candidate to some degree of interactivity, has been largely overlooked. Here follows three suggestions for new possibilities of IS, based on the narrative theory of possible worlds. More details can be found in Szilas et al. (2012).
According to (Louchart, Swartjes, Kriegel and Aylett, 2004) an emergent narrative establishes a cooperative contract with the interactor, and it is his decisions (interpretations) that determine the story landscape, and possible actions. Within the paradigm of emergent narrative, the denser the landscape the better (more story options). Eco considers the more a text is open and the less the contract of understanding is specified (between author and reader) the more possible worlds will result from the reader assuming the author's intention. In IS this is ideal especially concerning emergent narrative.
+
* Embedded story: One of the most visible “world creating” proposition is the fact that a character in a narrative tells a story. Such an embedded story is a fiction in a fiction. Within a first fictional world, the embedding world, a boundary is crossed and the reader/audience is transported into another world, the embedded world (Ryan, 1991). Applied to IS, embedded stories would consist in letting the user act in both the embedding and the embedded worlds. A Non Playing Character would "tell" an embedded story in a participative way, since the user would play one character in the embedded story. Several cases can be distinguished, depending on what crosses the boundary between the two worlds:
 +
** Worlds are strictly separate;
 +
** Some knowledge crosses the world;
 +
** Some material entities (characters, objects) can travel between worlds, creating strange effects such as the disappearance of one character.
 +
* Multiple actualization: With current IS systems, although the user imagines a multitude of possible worlds and is given choices at several points within the story (choice points), only one route is finally explored. If the user replays, he can explore another route, but each reading is distinct, and previous readings are not accessible during the current reading. The theory of possible worlds opens the possibility that when interacting with a story via a choice point, the user can, not only actualize one of his choices, but also explore other alternative routes. Explorations of these several alternative possible worlds occurs within the same reading session. Navigation between alternative possible worlds can be designed in various manners, depending on:
 +
** Who decide where the bifurcation points are, the user or the computer;
 +
** When the navigation is enabled;
 +
** Where, in a possible world, the user arrives (at the end of his previous exploration,  wherever he wants, etc.).
 +
* Optative interactive world: This type of world represents what a character desires. If interactive, such possible worlds would be similar to an alternative actualization (see above), except that this possible world would be biased by the desires of the character creating this subworld.
  
 
===Systems/Tools using this theory===
 
===Systems/Tools using this theory===
The Ideal Reader concept has been borrowed by [[IDtension]] to design the "model of the user".
+
All systems based on planning implicitly use possible worlds: [[I-Storytelling]], [[Fearnot]], [[Moe]], [[Gadin]], etc., but as explained above, explicit interaction with several possible worlds is still lacking in IDS.
  
 
===Links===
 
===Links===
* [http://www.signosemio.com/eco/a_cooperation.asp Textual cooperation, signosemio website]
+
* [http://hup.sub.uni-hamburg.de/lhn/index.php/Possible_Worlds Possible worlds], described by Marie-Laure Ryan in the living handbook of narratology.
  
 
===References===
 
===References===
*Eco, U., (1965). L'oeuvre ouverte. Paris: Le Seuil.
+
* Pavel, T. G. (1975). “Possible Worlds in Literary Semantics.” Journal of Aesthetics and Art Criticism 34, 165–76.
*Eco, U., (1985). Lector In Fabula: Le rôle du lecteur. Grasset.
+
* Ryan, M.-L. (1991). Possible Worlds, Artificial Intelligence, and Narrative Theory. Indiana University Press.
*Louchart S., Swartjes I., Kriegel M., and Aylett R., (2008). Purposeful Authoring for Emergent Narrative. Proceedings of the 1st Joint International Conference on Interactive Digital Storytelling: Interactive Storytelling. LNCS vol 5334. pp. 273 - 284.
+
* Szilas, N., Axelrad, M., Richle, U. (2012). [http://tecfa.unige.ch/perso/szilas/papers/SzilasAxelradRichle_IJCGT2010.pdf Propositions for Innovative Forms of Digital Interactive Storytelling Based on Narrative Theories and Practices]. In Z. Pan et al. (Eds.): Transactions on Edutainment VII,  LNCS 7145,  pp. 161--179. Springer,  Heidelberg (2012).

Latest revision as of 12:14, 3 February 2012

IRIS Wiki - Narrative Theories - Theory of possible worlds

Authors

Thomas Pavel, Marie-Laure Ryan, among others.

Histo-geographical placement

Last quarter of the 20th century.

Type of story

All types, including complex stories.

Parent Theories

Theory of Possible Worlds in Analytic Philosophy.

Child Theories

Brief Description

Possible worlds constitute a set of narratological theories that describe narrative in terms of several worlds. Each possible world (PW) is a set of elements that constitute a system. Worlds are interconnected to each other by various hierarchical relations (for example an element of a PW, a character, creates another PW by telling a story). Possible worlds have been formalized in logico-mathematical terms, with the particular goal to formalize the relations between these PWs. For example, what is the relation between W0 and WD? What is the accessibility between one possible world to the other? What is the logical truth of an element of WD? Etc.

Several kinds of PWs can be found in narrative:

  • The actual world (noted W0), in which the reader reads a book, the movie audience sees a movie and the audience and actors gather inside a theater.
  • The fictional or dramatic world (noted WD), that is described by the narrative, inhabited by characters, places, objects, and where narrative actions take places.
  • Spectators' subworlds, which are worlds that the reader constructs mentally as possible/anticipated worlds. They correspond to inferential walks described by U. Eco in his textual cooperation theory.
  • Characters' subworlds, generated by “world creating” propositions such as wish, hope, or imagine.
  • Alternate fictional worlds, which are parallel to WD, when the story explicitly tells several variations on a story so that to create several alternate fictional worlds (It's a wonderful Life (F. Capra), Smoking / No Smoking (A. Resnais), etc.).

Relation with Interactive Storytelling

For Interactive Storytelling, formalizing these possible worlds is a natural option. Artificial Intelligence research provides useful tools for that purpose. For example, the Expert System JESS offers the possibility to apply reasoning rules specific to a “world”, called a module. The very principle of planning is an exploration of possible worlds, in order to generate a solution (in WD) that satisfies some given constraints (such as enabling to reach a certain story goal). This relationship is well established in the book from Marie-Laure Ryan's research (Ryan, 1991). In agent-based planning, the plan explore character's subworlds. However, despite this strong relation between the theory of possible worlds and Artificial Intelligence, current AI algorithms make limited use of the possible worlds they generate. Generated possible worlds reman internal to the algorithms. What is being shown is a single world, WD, the best world according to the exploration of other possible worlds. For example, a character, based on possible world's exploration, could say: "If we let it in, the ship could be infected." (Alien movie, R. Scott); or "I you tell her the truth, she will be made at you and tell everything to your boss". Beyond planning mechanisms, the very fact that a single story can embed a multitude of possible worlds of different natures, each these subworlds being candidate to some degree of interactivity, has been largely overlooked. Here follows three suggestions for new possibilities of IS, based on the narrative theory of possible worlds. More details can be found in Szilas et al. (2012).

  • Embedded story: One of the most visible “world creating” proposition is the fact that a character in a narrative tells a story. Such an embedded story is a fiction in a fiction. Within a first fictional world, the embedding world, a boundary is crossed and the reader/audience is transported into another world, the embedded world (Ryan, 1991). Applied to IS, embedded stories would consist in letting the user act in both the embedding and the embedded worlds. A Non Playing Character would "tell" an embedded story in a participative way, since the user would play one character in the embedded story. Several cases can be distinguished, depending on what crosses the boundary between the two worlds:
    • Worlds are strictly separate;
    • Some knowledge crosses the world;
    • Some material entities (characters, objects) can travel between worlds, creating strange effects such as the disappearance of one character.
  • Multiple actualization: With current IS systems, although the user imagines a multitude of possible worlds and is given choices at several points within the story (choice points), only one route is finally explored. If the user replays, he can explore another route, but each reading is distinct, and previous readings are not accessible during the current reading. The theory of possible worlds opens the possibility that when interacting with a story via a choice point, the user can, not only actualize one of his choices, but also explore other alternative routes. Explorations of these several alternative possible worlds occurs within the same reading session. Navigation between alternative possible worlds can be designed in various manners, depending on:
    • Who decide where the bifurcation points are, the user or the computer;
    • When the navigation is enabled;
    • Where, in a possible world, the user arrives (at the end of his previous exploration, wherever he wants, etc.).
  • Optative interactive world: This type of world represents what a character desires. If interactive, such possible worlds would be similar to an alternative actualization (see above), except that this possible world would be biased by the desires of the character creating this subworld.

Systems/Tools using this theory

All systems based on planning implicitly use possible worlds: I-Storytelling, Fearnot, Moe, Gadin, etc., but as explained above, explicit interaction with several possible worlds is still lacking in IDS.

Links

  • Possible worlds, described by Marie-Laure Ryan in the living handbook of narratology.

References