Abondance de biens ... nuit.

Un domaine, prometteur semble-t-il, émerge actuellement en informatique : la Gestion des connaissances (Knowledge Management). Nous allons, dans ce chapitre, tenter de clarifier nos idées sur ce que peut être la gestion des connaissances et en quoi une machine peut nous aider.

Toutes les citations utilisées sont tirées de La Bibliothèque de Babel de Jorge Luis Borges [1] . Elles sont systématiquement placées en retrait.

Cette bibliothèque allégorique est censée contenir tous les livres du monde. A la réflexion, l'existence d'une telle bibliothèque n'est pas absurde en soi. Mais supposer cette existence implique de nombreuses conséquences sur le sens qu'on peut attribuer aux choses écrites.

Parler de cette bibliothèque hypothétique sera l'occasion de réfléchir sur ce que peuvent être des signes, des symboles, une information et une connaissance. En particulier, que pourrait signifier : être informé, partager une connaissance ?

Question : En supposant que vous naissiez quelque part dans cette bibliothèque, à partir de quand cesserez-vous de croire en les livres qu'elle contient ?

La plupart des points que nous allons soulever à présent relèvent de la linguistique. Cependant, nous allons conserver une approche naïve pour mettre notre intuition et notre bon sens à l'épreuve. Pour ceux qui souhaitent approfondir un peu plus ces question, nous pouvont les renvoyer au Cours de linguistique générale de Saussure, paru en 1916.

Hiéroglyphe et Symbole

Au moins à l'origine, le hiéroglyphe est naturellement porteur de sens, au moins en ce qui concernent les choses concrètes. Au moins à l'origine, les hiéroglyphes peuvent être créés au fur et à mesure des besoins sans que pour autant on cesse de les comprendre. Par définition, ces hiéroglyphes devraient pouvoir être compris par tous les humains, mais...

L'introduction du symbole a probablement été rendue nécessaire lorsqu'il est apparu qu'il n'était plus possible de percevoir le sens d'un hiéroglyphe simplement en le regardant. Il est clair que cette apparition a probablement été également considérée comme une formidable économie de moyens.

Question : A partir de quand, pourrait-on considérer à coup sûr, que les hiéroglyphes cessent d'être naturellement porteurs de sens ? Donnez quelques exemples.

Question : A quelle(s) condition(s) un hiéroglyphe peut-il être compris sûrement pas deux humains ? Donner quelques exemples de hiéroglyphes sûrement compris par certains humains et sûrement pas compris par d'autres.

Symboles et Information.

Le mot information a un sens sensiblement différent selon qu'on le considère dans la vie courante ou selon qu'on en considère la théorie associée. Pour les théoriciens, la notion d'information n'a pas de sens a priori, on va simplement se donner les moyens d'en mesurer une quantité. Cette mesure, introduite par Claude Shannon , va mesurer le degrés de surprise que provoque le message reçu : ce qui est prévisible n'apporte aucune information.

L'information ,contenue dans un message sera codée sous la forme d'une suite particulière de symboles et le principal problème qu'on se pose est soit de l'enregistrer sur un support soit de la transmettre de telle sorte qu'il soit possible de la reconstituer. Le fait qu'une information est susceptible de véhiculer un sens n'entre pas en ligne de compte.

La situation change radicalement lorsqu'on ne cherche pas simplement à transmettre un message mais qu'on cherche à la comprimer. La nécessité de la compression apparait dès qu'on se rend compte qu'on aimerait (a besoin) de transmettre toujours plus d'information dans un message de longueur donnée. A partir de là, on ne va chercher qu'à transmettre un message le plus utile possible.

La notion d'utilité peut recouvrir deux aspects :

• la suite de symboles à transmettre étant finie, ont peut lui associer une certaine quantité d'information. On pourra alors considérer que certains symboles ne font que renforcer cette information ; ils ne sont donc pas nécessaires et ils constituent une redondance qu'on peut éliminer à l'émission car il sera possible de la recréer à la réception. On parlera, dans ce cas, de compression sans perte. La méthode de compression sans perte la plus connue est probablement l'algorithme de Lempel et Ziv utilisé par les formats bien connus : .zip et .gif.
• la suite des symboles à transmettre peut être interprétée. On pourra alors considérer que la méthodes de compression est sans perte si l'interprétation avant et après la transmission est la même ou si la méthode de compression entraîne une perte d'interprétation considérée comme acceptable. On parlera, dans ce cas, de compression avec pertes. La méthode de compression avec perte la plus connue est probablement celle utilisée par les format JPEG [2].

En reprenant les considérations qui ont été introduites au chapitre 5, on peut résumer la situation ainsi :

• une données est une expressions bien formée,
• une message utile est un théorème (interprétable).

Cette nuance peut être illustrée par cette citation de Roger Schank [3] tirée de Information is surprise :

Information et Connaissance.

Passer du concept d'information au concept de connaissance n'est pas aisé. Si l'information est une forme d'abstraction des messages, la connaissance semble être une abstraction de l'information. En quelque sorte, la connaissance serait une méta-interprétation.

Cette méta-interprétation a été étudiée selon plusieurs schémas. Deux sont typiques :

• les réseaux sémantiques.
• les scripts.

Réseaux sémantiques

Dans ces réseaux, présentés sous forme de graphes, des concepts sont reliés entre eux par des relations. Ces relations peuvent être des relations de structuration : est-une-espèce-de, est-une-partie-de ou des relations de comportement. Dans ce cas elles décrivent une action : mange, marche-sur... Les réseaux sémantiques ont un fondement théorique solide mais leur pouvoir expressif est finalement assez faible.

Scripts

The central focus of Schank's theory (:cell PQA(PSS(of scripts):) has been the structure of knowledge, especially in the context of language understanding. Schank (1975) outlined contextual dependency theory which deals with the representation of meaning in sentences.

Building upon this framework, Schank & Abelson (1977) introduced the concepts of scripts, plans and themes to handle story-level understanding. Later work (e.g., Schank, 1982,1986) elaborated the theory to encompass other aspects of cognition.

The key element of conceptual dependency theory is the idea that all conceptualizations can be represented in terms of a small number of primative acts performed by an actor on an object. For example, the concept, "John read a book" could be represented as: John MTRANS (information) to LTM from book, where MTRANS is the primative act of mental transfer.

In Schank's theory, all memory is episodic, i.e., organized around personal experiences rather than semantic categories. Generalized episodes are called scripts -- specific memories are stored as pointers to scripts plus any unique events for a particular episode.

Scripts allow individuals to make inferences needed for understanding by filling in missing information (i.e., schema). Schank (1986) uses script theory as the basis for a dynamic model of memory. This model suggests that events are understood in terms of scripts, plans and other knowledges structures as well as relevant previous experiences. An important aspect of dynamic memory are explanatory processes (XPs) that represent sterotyped answers to events that involve analomies or unusual events. Schank proposes that XPs are a critical mechanism of creativity .

Scope/Application: Script theory is primarily intended to explain language processing and higher thinking skills. A variety of computer programs have been developed to demonstrate the theory. Schank (1991) applies his theoretical framework to story telling and the development of intelligent tutors. Shank & Cleary (1995) describe the application of these ideas to educational software.

Une certaine vision du monde

Notes

1. (retour) Jorge Luis Borges (1899-1986) Argentine poet, essayist, and short-story writer whose tales of fantasy and dreamworlds have become classics of the 20th-century world literature. Borges was profoundly influenced by European culture, English literature, and such thinkers as Berkeley.
   
   Most of Borges's tales can only be understod in universal terms - the circular labyrinth as symbol of life is found in several of his works. International fame Borges gained when he shared the International Publishers' Formentor Prize along with Samuel Beckett. Although his name was mentioned in speculations about Nobel Prize, Borges never became a Nobel Laureate.
   
   Jorge Luis Borges was born in Buenos Aires. His family included British ancestry and he learned English before Spanish. His father, a lawyer and educator, explored the works of the Irish philosopher George Berkeley with his son and demonstrated the paradoxes of Zeno on a chessboard.
   
   In 1914 Borges moved with his family to Geneva, where he learned French and German and received his B.A. from the Collège of Geneva.
   
   From 1918 Borges was in Spain, where he was a member of avant-garde Ultraist literary group.
   
   In 1921 Borges settled in Buenos Aires and started his carees as a writer publishing poems and essays in literary journals. He was co-founding editor of the journals Proa (1924-26) and Sur, and contributed also to Prisma. He served as literary adviser for the publishing house Emecé Editores, and wrote weekly columns for El Hogar from 1936 to 1939. As a critic he wrote original interpretations of the Argentine classics and displayed a vast knowledge of European and American literature. As a poet Borges made his debut with FERVOR DE BUENOS AIRES, which appeared in 1923. In 1938 his father died, a great blow because the two had been unusually close. Borges also suffered a severe head wound and after recovery the experience freed in him deep forces of creativity.
   
   His first collection of the intricate and fantasy-woven short stories, EL JARDÍN DE SENDEROS QUE SE BIFURCAN, was published in 1941. Later collections include FICCIÓNES (1944), EL ALEPH (1949), and EL EL HACEDOR (1960). Borges's interest in fantasy was shared by another well-known Argentine writer of fiction, Adolfo Bioy Casares, with whom Borges coauthored several collections of tales between 1942 and 1967.
   
   From 1939 to 1946 Borges was a municipal librarian, but he was fired from his post by the Péron regime, and between the years 1946 and 1954 he was a poultry inspector for Buenos Aires Municipal Market. An attempt was made to bomb the house where Borges and his mother lived. After Peron's deposition Borges was appointed Director of the National Library (1955-1973). "I speak of God's splendid irony in granting me at once 800 000 book and darkness," Borges noted alluding to his now almost complete blindness. Borges also was professor of literature at the University of Buenos Aires, and taught there from 1955 to 1970.
   
   In 1961 Borges shared the Prix Formentor with Samuel Beckett, and started his series of visits to countries all around the world, and continued traveling until his death. In 1967 Borges began a five-year period of collaboration with Norman Thomas di Giovanni, and gained new fame in the English-speaking world. When Juan Perón was again elected president in 1973, Borges resigned as director of the National Library. Despite his opposition to Perón and later to the junta, his support to liberal causes were considered too ambiguous. Borges, who had suffered eye problems, become totally blind in his last decades.
   
   He had a congenital defect that had afflicted several generations on his father's side of the family. However, he published several books, among them EL LIBRO DE LOS SERES IMAGINARIOS (1967), EL INFORME DE BRODIE (1970), and EL LIBRO DE ARENA (1975). After the death of his mother, who had been his constant companion, Borges began travelling ferishly. Borges died on June 14, 1986 in Geneva, Switzerland.
   
   He was married twice. In 1967 he married his old friend, the recently widowed Elsa Asteta Millán, a relationship that lasted three years. After the divorce, Borges moved back in with his mother. His last years Borger lived with María Kodama, whom he married in 1986. Together, they travelled around the world, producing in 1984 an account of their journey, with text by Borges and photographs by Kodoma. Borges's fictional universe stems from his varied and often esoteric readings in literaure, philosophy, and theology. The philosophical theories of Berkeley and Schopenhauer influenced greatly his writings, and the mysterious theological labyrinths of Gnosticism and the Cabala have reinforced many of his plots. Borges saw man's search for meaning in an infinite universe absurd, he used old myths to convey contemporary themes, and added footnotes in order to feign authenticity or to mock erudition.
   
   For Borges concrete reality may consist only of mental perceptions. His classical short story 'La muerte y la brújula' portrayed an excessively rational detective, Lönnrot (referring to the philologist/poet Elias Lönnrot, the collector of Kalevala poems), who finds himself trapped in a cerebral labyrinths ow his own making while attempting to solve a series of crimes. In 'La Biblioteca de Babel' the symmetrically structured library represented the universe as it is conceived by rational man, and the library's illegible books referred to man's ignorance. In 'Tlön, Uqbar, Orbis Tertius' Borges invented a whole other universe based on an imaginary encyclopedia. The narrator tates, that 'Tlön is surely a labyrinth, but it is a labyrinth devised by men, a labyrinth destined to be deciphered by men."
   
   As an essayist Borges adopted a literary culture almost alien to Latin American literature, and brought attention to ancient philosophers and mystics, Jewish cabbalist and gnostics, forgotten French poets, the Finnish national epos Kalevala, and above all such English writers as John Milton, Samuel Taylor Coleridge, G.K. Chesterton and John Keats. His output of essays was not extensive. The key books were DISCUSIÓN (1932), HISTORIA DE LA ETERNIDAD (1936), and OTRAS INQUISICIONES (1952). Characteristic for Borges's essays was that on interpreting other writers' texts he gave them new meaning, and invitated the reader to think in a way not commonly accepted. When many Latin American writers dealt with political or social subjects, Borges represented a quiet intellectual dissidence.
2. (retour) Joint Picture Expert Group. A l'origine d'une méthode de compression utilisée pour les cliché photographiques et pour les images possédant des dégradés de couleur. Cette méthode de compression est utilisée également dans la norme de compression MPEG-1 (Moving Pictures Expert Group) utilisée pour la transmission et le stockage de séquences vidéo.
   
   Le format MP3 est très connu des habitués d'Internet car c'est celui utilisé pour compresser la bande-son d'une séquence vidéo (norme MPEG-3) détourné avec succcès pour compresser de la musique.
3. (retour) Roger Schank is a computer scientist and cognitive psychologist who has worked in the AI field for twenty-five years. Like Marvin Minsky, he takes the strong AI view, but rather than trying to build an intelligent machine he wants to deconstruct the human mind. He wants to know, in particular, how natural language — one's mother tongue — is processed, how memory works, and how learning occurs. Schank thinks of the human mind as a learning device, and he thinks that it is being taught in the wrong way. He is something of a gadfly; he deplores the curriculum-based, drill-oriented methods in today's schools, and his most recent contributions have been in the area of education, looking at ways to use computers to enhance the learning process.
   
   Roger Schank, a leading Artificial Intelligence researcher, is the Chairman and CTO for Cognitive Arts and has been the Director of the Institute for the Learning Sciences since its founding in 1989. He holds three faculty appointments at Northwestern University as John Evans Professor of Computer Science, Education, and Psychology. Previously, he was Professor of Computer Science and Psychology at Yale University and Director of the Yale Artificial Intelligence Project. His books include: Dynamic Memory: A Theory Of Learning In Computers And People , Tell Me A Story: A New Look At Real And Artificial Memory, The Connoisseur's Guide To The Mind, And Engines For Education and Virtual Learning: A Revolutionary Approach To Building A Highly Skilled Workforce.