Conceptual Dependency KR Chowdhary, Professor, Department of - PowerPoint PPT Presentation

Conceptual Dependency KR Chowdhary, Professor, Department of Computer Science & Engineering, MBM Engineering College, JNV University, Jodhpur, Dept. of CSE, MBM Engg.

K NOWLEDGE R EPRESENTATION: 1970 ’S : Conceptual Dependency Grammar A number of authors in AI have addressed the question of the 'concept'-based organisation of knowledge and we use two examples to illustrate this. •We consider a verb-oriented organisation of knowledge proposed by Schank: Conceptual Dependency Grammar. Dept. of CSE, MBM Engg.

K NOWLEDGE R EPRESENTATION: 1970 ’S : Conceptual Dependency Grammar Conceptual dependency (or CD) is a theory of how to represent the meaning of natural language sentences in a way that: • First, facilitates for drawing inferences from the sentences. • Second, it has been argued that the representation (CD) is independent of the language in which the sentences were originally stated Dept. of CSE, MBM Engg.

K NOWLEDGE R EPRESENTATION: 1970 ’S : Conceptual Dependency Grammar •Schank's (1975) Conceptual Dependency Theory was developed as a part of a natural language comprehension project. •Schank's claim was that sentences can be translated into basic concepts expressed as a small set of semantic primitives. •Conceptual dependency allows these primitives, which signify meanings, to be combined to represent more complex meanings. •Schank calls the meaning propositions underlying language "conceptualisations". Dept. of CSE, MBM Engg.

Roger Schank’s project is the ‘representation of meaning in an unambiguous language-free manner’ (1973). ‘Any two utterances that can be said to mean the same thing, whether they are in the same or different languages, should be characterised in only one way by the conceptual structure’ (1973) (CG) Three elemental kinds of concepts: a nominal and an action together with their modifiers Dept. of CSE, MBM Engg.

Three elemental kinds of concepts: can be       1. Concept a nominal • an abstract or concrete object that invokes an image; • cars are concrete objects; • gravity is an abstract concept; • a nominal produces a picture (PP) Dept. of CSE, MBM Engg.

can be       2. Concept an action • what a nominal does? • something an animate nominal does to an object; • there are primitive ACTions and derived ACTions; Dept. of CSE, MBM Engg.

can be       3. Concept a modifier • a modifier modifies a nominal or an action; • a modifier specifies an action or a nominal; Dept. of CSE, MBM Engg.

can be       3a Concept a picture modifier or aider (PA) blue • a car PA can be       3b Concept an action modifier or aider (AA) quickly • he run AA Dept. of CSE, MBM Engg.

CD theorists argue that 'the CD representation of a sentence is built not out of primitives corresponding to the words used in the sentence, but rather out of conceptual primitives that can be combined to form the meanings of words in any particular language' CD Building Blocks Primitive Acts Primitive conceptual categories Conceptual Tenses Diagrammatic conventions Dept. of CSE, MBM Engg.

Conceptual Categories Three elemental kinds of concepts – conceptual categories (PP, ACT, PA and AA) – relate to each other in specified ways. These relations are called dependencies by Schank. Dept. of CSE, MBM Engg.

Conceptual Categories In a dependency relation, one partner or item is dependent and the other dominant or governing; a governor  dependent is a partially ordered relationship • A dependent must have a governor and is understood in terms of the governor • A governor may or may not have dependent(s) and has an independent existence • A governor can be a dependent PP and ACT are inherently governing categories, PA and AA are inherently dependent. Dept. of CSE, MBM Engg.

Conceptual Categories For a conceptualisation to exist, there must be at least two governors: Sally stroked her fat cat ‘Sally’ name of an object (nominal  PP) ‘stroked’ name of an action (ACT) PP: Sally, cat, her [Sally] ACT: to stroke PA: fat Governors: Sally, stroke, cat Dependent: PP (cat) on ACT (stroke) PA (fat) on PP (cat) PP (cat) on PP (her[Sally]) Dept. of CSE, MBM Engg.

Conceptual Categories Sally stroked her fat cat 1. Sally and stroking are necessary for conceptualisation: there is a two-way dependency between each other: Sally  stroke 2. Sally’s cat cannot be conceptualised without the ACT stroke  it has an objective dependency on stroke  O  Sally  stroke cat. Dept. of CSE, MBM Engg.

Conceptual Categories Sally stroked her fat cat 3. The concept ‘cat’ is the governor for the modifier ‘fat’:  O  Sally  stroke cat  fat Dept. of CSE, MBM Engg.

Conceptual Categories Sally stroked her fat cat 4. The concept PP(cat) is also governed by the concept PP(Sally) through a prepositional dependency : Sally  stroke cat  O   POSS-BY fat Sally[her] A Conceptual Dependency Network Dept. of CSE, MBM Engg.

Conceptual Cases Dependents that are required by an ACT are called Conceptual Cases : Consider the following sentences: Objective Case (O) 1. John took the book  O  PP[John]  ACT[took] PP[book] Recipient Case (R) 2. John took the book from Mary PP[John] R  PP ACT o < PP[Mary] PP Dept. of CSE, MBM Engg.

Conceptual Cases Instrumental Case (I) 3. John ate the ice cream with a spoon PP[John]  I  PP[John]  ACT [eat]  do o o PP[ice cream] PP[spoon] Dept. of CSE, MBM Engg.

Conceptual Cases Directive Case Relation (D) 4. John drove his car to London from Guildford John  do London D   car  drove  POSS-BY < Guildford John ( ) indicates causality Dept. of CSE, MBM Engg.

Prepositional Dependency Consider the following sentences: Possession This is Sally’s cat  one PP (Sally) provides specific information • about another PP (cat) - Cat  POSS-BY Sally Location • Sally is in London - London  LOC Sally Containment • The glass contains water - Water  CONT Glass Dept. of CSE, MBM Engg.

Underlying ACTs Giving and Taking OR just TRANSferring I took a book from Sally PP[I] R PP [I]  ATRANS < PP[Sally] o PP [book] Dept. of CSE, MBM Engg.

Sentence = ‘I took a book from Sally’ CD Building Block Elaboration Primitive Acts ATRANS indicates transfer (of possession) Primitive conceptual Objects (Picture Producers: PP): Categories Sally, I , book Conceptual Tenses o indicates object case relation; R indicates recipient case relation Diagrammatic Conventions Arrows indicate the direction of dependency Double arrow indicates two way link between actor and action Dept. of CSE, MBM Engg.

Underlying ACTions Primitive Act Elaboration Transfer of an abstract relationship such as possession ownership or ATRANS control (give) Transfer of the physical location of an object (go) PTRANS Application of a physical force to an object (push) PROPEL Movement of a body part of an animal by that animal (kick) MOVE Grasping of an object by an actor (grasp) GRASP Taking in of an object by an animal to the inside of that animal (eat) I NGEST Expulsion of an object from the object of an animal into the physical EXPEL world (cry) Transfer of mental information between animals or within an animal (tell) MTRAN S Construction by an animal of new information of old information (decide) MBUI LD Conceptualise or think about an idea (think) CONC Actions of producing sounds (say) SPEAK Action of attending or focusing a sense organ towards a stimulus (listen) ATTEND Dept. of CSE, MBM Engg.

Underlying ACTs I gave a book to Sally Sally R I  gave < I o book PP[Sally] R PP [I]  ATRANS < PP[I] o PP [book] Dept. of CSE, MBM Engg.

Underlying ACTs – The TRANSfer ACT •Transfer of an abstract relationship: possession of property  give, take; Abstract TRANSfer (ATRANS) •Transfer of the physical location of an object  go, come; Physical TRANSfer (PTRANS) •Transfer of mental information  ask, tell; Mental TRANSfer (MTRANS) Dept. of CSE, MBM Engg.

Underlying ACTs – STATI CS and DYNAMI CS •PROPELling an object by applying physical force  push, pull; PROPEL •MOVEment of a body part by its owner  kick; MOVE •GRASPing of an object by an actor  catching, clutching; GRASP Dept. of CSE, MBM Engg.

Underlying ACTs – Sustaining life; processing things •INGESTing of an object by an animal  eat, drink; INGEST •EXPELling of something from a body of an animal  crying [tears] Dept. of CSE, MBM Engg.

Underlying ACTs – Stimulus and Response •Mentally BUILDing new information out of old  deciding, inferring; MBUILD •SPEAKing by producing sounds  talking; SPEAK •ATTENDing to a stimulus by focusing a sense organ towards it  seeing, hearing; ATTEND Dept. of CSE, MBM Engg.

Conceptual Tenses Any conceptualisation can be modified as a whole by a conceptual tense . John took the book – John  took – can be denoted by looking at the lemma take (from which the past tense took was derived): p(ast)  take John Dept. of CSE, MBM Engg.