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— CH. 1 · MINSKY'S FOUNDATIONAL PROPOSAL —

Frame (artificial intelligence)

~4 min read · Ch. 1 of 6
6 sections
  • In June 1974, Marvin Minsky published a paper titled A Framework for Representing Knowledge at the MIT Artificial Intelligence Laboratory. The document introduced frames as a method to handle stereotyped situations that computers struggle to process. Before this proposal, researchers faced huge solution spaces even for simple tasks like extracting phonemes from audio or detecting object edges. Minsky argued that humans use stored knowledge to interpret new cognitive situations quickly. His work suggested that establishing context could automatically reduce possible search space significantly. This approach aimed to make computer systems more efficient by mimicking human thought patterns rather than relying solely on rigid logic.

  • Each frame contains information about how to use it and what to expect next when expectations are not met. Information within these structures divides into two categories: unchanging data and terminals that usually change. Terminals function similarly to variables in programming languages. Top-level frames carry facts always true about a problem while terminals hold values that might shift with new information. Different frames can share the same terminals allowing for flexible connections between concepts. Every piece of information holds inside a slot which acts as a container for specific details. These slots store facts, data values called facets, procedures known as procedural attachments, default values, and other frames or subframes. An IF-NEEDED mechanism allows deferred evaluation while an IF-ADDED rule updates linked information automatically.

  • The earliest frame-based languages were custom developed for specific research projects without being packaged as reusable tools. Researchers soon realized the benefits of extracting core infrastructure to create general-purpose frame languages independent of specific applications. One of the first such languages was KRL followed by KL-ONE which became one of the most influential early systems. Robert MacGregor at the Information Sciences Institute later developed Loom as a widely used successor to KL-ONE. During the 1980s business interest in artificial intelligence fueled by expert systems led to commercial products like Intellicorp's Knowledge Engineering Environment or KEE. This tool provided a full frame language with multiple inheritance slots triggers default values and a rule engine supporting backward and forward chaining. The Semantic Web research agenda later spawned renewed interest in automatic classification leading to standards like OWL or Web Ontology Language. Stanford University released Protege as open source software built on OWL though it ceased explicit frame support after version 3.5.

  • Frame languages share significant overlap with object-oriented languages despite different fundamental design goals. Developers moving from academic labs to the commercial world tended to ignore philosophical issues focusing instead on specific capabilities. Both paradigms arrived at representing primary software objects in taxonomies starting with very general types progressing to more specific ones. The primary difference lay in how much encapsulation each community considered critical for success. For object-oriented programming encapsulation remained one if not the most critical requirement to manage large complex systems. Frame language creators prioritized providing vast arrays of tools to represent rules constraints and logic over strict encapsulation. Multiple inheritance served as another main differentiator since frame languages required allowing frames or classes to have two or more superclasses. Many object-oriented languages eventually preferred single inheritance to maintain modularity even though early frame languages lacked message passing until developer demands forced changes.

  • Early work on frames drew inspiration from psychological research dating back to the 1930s showing people use stored stereotypical knowledge to interpret new situations. Researchers like Schank and Abelson used frames to illustrate how AI systems could process common human interactions such as ordering a meal at a restaurant. These scholars were less interested in mathematical formality believing formalisms did not model average human conceptualization well. Ron Brachman represented the opposing view seeking mathematical precision through First Order Logic and Set Theory. This conflict created a classic divide known as neats versus scruffies within artificial intelligence research. Neats valued mathematical precision while scruffies focused on intuitive psychologically meaningful representations. The KL-ONE language exemplified the formal approach by spawning subsequent frame languages with automated reasoning capabilities called classifiers. Classifiers analyze declarations defining sets subsets relations and automatically deduce additional relations detecting inconsistencies within models.

  • Classification technology originally developed for frame languages became a key enabler of the Semantic Web vision. The Internet contains highly informal unstructured data making it impossible to require all systems to standardize on one data model. Automatic classification provides developers with powerful tools to bring order and consistency to inconsistent collections of information found online. The goal involves organizing web pages not just by text keywords but by classification of concepts into ontologies. Standards like OWL provide semantic layers on top of the internet allowing users to specify concepts without worrying about homonyms or synonyms crowding search results. For instance searching for OWL today retrieves pages about birds rather than the Web Ontology Language standard. The Linking Open Data community emerged from this research focusing on exposing data on the web rather than modeling. Protege remains an active ontology editing tool though current versions prioritize OWL DL over explicit frames due to expressiveness requirements.

Common questions

When did Marvin Minsky publish the paper introducing frames?

Marvin Minsky published A Framework for Representing Knowledge in June 1974 at the MIT Artificial Intelligence Laboratory. This document introduced frames as a method to handle stereotyped situations that computers struggle to process.

What are the two categories of information within frame structures?

Information within these structures divides into unchanging data and terminals that usually change. Terminals function similarly to variables in programming languages while top-level frames carry facts always true about a problem.

Which early frame-based language became one of the most influential systems after KRL?

KL-ONE became one of the most influential early systems following KRL. Robert MacGregor later developed Loom as a widely used successor to KL-ONE at the Information Sciences Institute.

How do frame languages differ from object-oriented languages regarding inheritance?

Frame languages required allowing frames or classes to have two or more superclasses through multiple inheritance. Many object-oriented languages eventually preferred single inheritance to maintain modularity even though early frame languages lacked message passing until developer demands forced changes.

Who were the researchers that used frames to illustrate how AI systems could process common human interactions?

Researchers like Schank and Abelson used frames to illustrate how AI systems could process common human interactions such as ordering a meal at a restaurant. These scholars were less interested in mathematical formality believing formalisms did not model average human conceptualization well.

All sources

18 references cited across the entry

  1. 1journalA Framework for Representing KnowledgeMarvin Minsky — 1974
  2. 2webFOAF
  3. 3journalAn Overview of KRL: A Knowledge Representation LanguageD.G. Bobrow — 1977
  4. 4journalA Structural Paradigm for Representing KnowledgeRon Brachman — 1978
  5. 5journalUsing a description classifier to enhance knowledge representationRobert MacGregor — June 1991
  6. 8webThe Unified Modeling LanguageEssential Strategies Inc. — 1999
  7. 9webRetrospective on LoomRobert Macgregor — Information Sciences Institute — August 13, 1999
  8. 10webOMG Formal SpecificationsObject Management Group
  9. 11bookRemembering: A Study in Experimental and Social PsychologyF. C. Bartlett — Cambridge University Press — 1932
  10. 12bookThe Psychology of Computer VisionMarvin Minsky — McGraw Hill — 1975
  11. 13bookScripts, Plans, Goals, and UnderstandingRoger Schank — Lawrence Erlbaum — 1977
  12. 14bookThe Handbook of Artificial Intelligence, Volume IIIEdward Feigenbaum — Addison-Wesley — September 1, 1986
  13. 16bookAI: The Tumultuous Search for Artificial IntelligenceDaniel Crevier — Basic Books — 1993