SHRDLU

SHRDLU

SHRDLU was an early natural language understanding computer program, developed by Terry Winograd at MIT from 1968-1970. It was written in the Micro Planner and Lisp programming language on the DEC PDP-6 computer and a DEC graphics terminal. Later additions were made at the computer graphics labs at the University of Utah, adding a full 3D rendering of SHRDLU's "world".

The name SHRDLU was derived from ETAOIN SHRDLU, the arrangement of the alpha keys on a Linotype machine, arranged in descending order of usage frequency in English.

Functionality

SHRDLU allowed user interaction using English terms. The user instructed SHRDLU to move various objects around in a small "blocks world" containing various basic objects: blocks, cones, balls, etc. What made SHRDLU unique was the combination of four simple ideas that added up to make the simulation of "understanding" far more convincing.

One was that SHRDLU's world was so simple that the entire set of objects and locations could be described by including as few as perhaps 50 words, nouns like "block" and "cone", verbs like "place on" and "move to", and adjectives like "big" and "blue". The possible combinations of these basic language building blocks were quite simple, and the program was fairly adept at figuring out what the user meant.

SHRDLU also included a basic memory to supply context. One could ask SHRDLU to "put the green cone on the red block" and then "take the cone off"; "the cone" would be taken to mean the cone one had just talked about. SHRDLU could search back further to find the proper context in most cases when additional adjectives were supplied. One could also ask questions about the history, for instance one could ask "did you pick up anything before the cone?"

A side effect of this memory, and the original rules SHRDLU was supplied with, is that the program could answer questions about what was possible in the world and what was not. For instance, SHRDLU would deduce that blocks could be stacked by looking for examples, but would realize that triangles couldn't be stacked, after having tried it. The "world" contained basic physics to make blocks fall over, independent of the language parser.

Finally, SHRDLU could also remember names given to objects, or arrangements of them. For instance one could say "a steeple is a small triangle on top of a tall rectangle"; SHRDLU could then answer questions about steeples in the blocks world, and build new ones.

Excerpt

Here is an extract from a famous demonstration of SHRDLU (with messages converted from their original upper case for ease of reading):

Person: Pick up a big red block.
Computer: OK.
Person: Grasp the pyramid.
Computer: I don't understand which pyramid you mean.
Person (changing their mind): Find a block which is taller than the one you are holding and put it into the box.
Computer: By "it", I assume you mean the block which is taller than the one I am holding.
Computer: OK.
Person: What does the box contain?
Computer: The blue pyramid and the blue block.
Person: What is the pyramid supported by?
Computer: The box.
Person: How many blocks are not in the box?
Computer: Four of them.
Person: Is at least one of them narrower than the one which I told you to pick up?
Computer: Yes, the red cube.
etc.

Consequences

The result was a tremendously successful demonstration of AI. This led other AI researchers to excessive optimism which was soon lost when later systems attempted to deal with more realistic situations with real-world ambiguity and complexity. Continuing efforts in the original SHRDLU stream have tended to focus on providing the program with considerably more information from which it can draw conclusions, leading to efforts like Cyc.

ee also

* Planner programming language

References

* "Procedures as a Representation for Data in a Computer Program for Understanding Natural Language". MIT AI Technical Report 235, February 1971

External links

* [http://hci.stanford.edu/~winograd/shrdlu/ SHRDLU] - Terry Winograd's SHRDLU page, includes source code
* [http://www.semaphorecorp.com/misc/shrdlu.html SHRDLU resurrection] - re-written versions of SHRDLU, including a Java3D version


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  • SHRDLU — Saltar a navegación, búsqueda SHRDLU es un programa de computadora para la comprensión del lenguaje natural. Fue desarrollado por Terry Winograd en el MIT entre los años 1968 y 1970. Fue implementado con los lenguajes de programación Micro… …   Wikipedia Español

  • SHRDLU — SHRDLU  ранняя программа понимания естественного языка, разработанная Терри Виноградом в MIT в 1968 1970 годах. Она была написана на языках Micro Planner и Лисп на компьютере DEC PDP 6 и использовала графический терминал DEC. Впоследствии в… …   Википедия

  • SHRDLU — war eines der ersten Computerprogramme, das Sprachverständnis und die Simulation planvoller Tätigkeiten miteinander verband. Es wurde 1972 von Terry Winograd entwickelt und erlaubte die Manipulation simulierter Bauklötze in einer imaginären… …   Deutsch Wikipedia

  • SHRDLU — (KI) Mikrowelt Programm zur Erforschung der natürlichen Sprache von Terry Winograd 1973, benannt nach dem Code ETAOIN SHRDLU , womit LINOTYPE Setzer Satzfehler in Zeitungsspalten markierten und der keine tiefere Bedeutung besitzt …   Acronyms

  • SHRDLU — (KI) Mikrowelt Programm zur Erforschung der natürlichen Sprache von Terry Winograd 1973, benannt nach dem Code ETAOIN SHRDLU , womit LINOTYPE Setzer Satzfehler in Zeitungsspalten markierten und der keine tiefere Bedeutung besitzt …   Acronyms von A bis Z

  • shrdlu — …   Useful english dictionary

  • ETAOIN SHRDLU — is the approximate order of frequency of the twelve most commonly used letters in the English language, best known as a nonsense phrase that sometimes appeared in print in the days of hot type publishing due to a custom of Linotype machine… …   Wikipedia

  • ETAOIN SHRDLU — sind die zwölf am häufigsten genutzten Buchstaben der englischen Sprache. Dies ist leicht verschieden von der Buchstabenhäufigkeit in Wörterbucheinträgen. Die gesamte Sequenz ist ETAOIN SHRDLU CMFWYP VBGKQJ XZ Drucksatz Tastatur einer Linotype… …   Deutsch Wikipedia

  • ETAOIN SHRDLU — (произносится [ˈɛteiˌɔɪn ˈʃrədlu] «итэоин шердлу», в русском языке известнее как «этаоин шрдлу»)  ряд из двенадцати букв, расположенный по убыванию частоты их использования в английском языке, бессмысленная фраза, которая иногда появлялась в …   Википедия

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