AI Lecture72006

Artificial IntelligenceRepresenting Commonsense Knowledge: 

Artificial Intelligence Representing Commonsense Knowledge L. Manevitz

Definitions : 

Definitions Representation – a set of syntactic and semantic conventions that make it possible to describe things. Syntax – specifies the symbols that may be used and the ways those symbols may be arranged. Semantics – specifies how meaning is embodied in the symbol arrangements allowed by the syntax.

Semantic Network Approach : 

Semantic Network Approach Nodes and Slots: Nodes are objects, or classes, or properties. Slots are of different types.

A Semantic Network : 

A Semantic Network Is-a has-part instance team uniform-color

Representing Nonbinary Predicates: 

Representing Nonbinary Predicates Unary Predicates can be rewritten as binary ones. man(Marcus) could be rewritten as instance(Marcus,Man)

Representing Nonbinary Predicates cont.: 

Representing Nonbinary Predicates cont. N-Place Predicates score(Cubs,Dodgers,5-3) becomes Is-a score home-team visiting-team

A Semantic Net Representing a Sentence: 

A Semantic Net Representing a Sentence “John gave the book to Mary.” object beneficiary agent instance instance

Some Important Distinctions: 

Some Important Distinctions First try: Second try: height height height greater-than

Some Important Distinctions cont.: 

Some Important Distinctions cont. Third try: value height height greater-than

Partitioned Semantic Nets: 

Partitioned Semantic Nets Is-a victim assailant Is-a Is-a The dog bit the mail carrier.

Partitioned Semantic Nets cont.: 

Partitioned Semantic Nets cont. Every dog has bitten a mail carrier. Is-a victim assailant Is-a Is-a Is-a form SA S1

Partitioned Semantic Nets cont.: 

Partitioned Semantic Nets cont. Every dog in town has bitten the constable. Is-a victim assailant Is-a Is-a Is-a form SA S1

Partitioned Semantic Nets cont.: 

Partitioned Semantic Nets cont. Every dog has bitten every mail carrier. Is-a victim assailant Is-a Is-a Is-a form SA S1

Inheritance : 

Inheritance Is-a slot – appears between objects and classes. ako slot – appears between subsets.

Inheritance -Procedure: 

Inheritance -Procedure F the given node; S the given slot; Form a Queue of F and all class nodes connected to F via Is-A node. F is at top of Queue. Until Queue is empty or default has been found determine if the first element of Queue has a value in its S slot: Yes – a value has been found. No – remove the first element from Queue and add the nodes related to the first element by AKO slots to the end of Queue. If a value has been found say that this is the default value of F’s S slot. Otherwise announce Failure.

Inheritance - Example : 

Inheritance - Example Is-a shape ako Is-a ako shape

If-needed Inheritance -Procedure: 

If-needed Inheritance -Procedure F the given node; S the given slot; Form a Queue of F and all class nodes connected to F via Is-A node. F is at top of Queue. Until Queue is empty or successful if-needed procedure has been found determine if the first element of Queue has a procedure in the If-Needed facet of its S slot: Yes – if the procedure produces a value than a value has been found. No – remove the first element from Queue and add the nodes related to the first element by AKO slots to the end of Queue. If a value has been found say that the value found is the value of F’s S slot. Otherwise announce Failure.

If-needed Inheritance - Example: 

If-needed Inheritance - Example Weight (if-needed) Volume Density

Example cont.: 

Example cont. Weight Volume Density Weight is activated by request for the weight of Brick12 !

Default Inheritance Procedure: 

Default Inheritance Procedure F the given node; S the given slot; Form a Queue of F and all class nodes connected to F via Is-A node. F is at top of Queue. Until Queue is empty or default has been found determine if the first element of Queue has a value in the Default facet of its S slot: Yes – if the first element has a value than a value has been found. No – remove the first element from Queue and add the nodes related to the first element by AKO slots to the end of Queue. If a value has been found say that the value found is the default value of F’s S slot. Otherwise announce Failure.

Default Inheritance - Example: 

Default Inheritance - Example Is-a Color (Default) ako Is-a ako Color (Default) Has no default color therefore probably Blue because of Block’s default color !

Perspective -Example: 

Perspective -Example Is-a Purpose Is-a shape Purpose Is-a Purpose Is-a

Special Links - Summary: 

Special Links - Summary IS-A and AKO links make class membership and subclass-class relations explicit, facilitating the movement of knowledge from one level to another. VALUE facets make values explicit.

Special Links – Summary cont.: 

Special Links – Summary cont. IF-NEEDED facets make procedures purposes explicit, and they relate procedures to the classes those procedures are relevant to. DEFAULT facets make likely values explicit without implying certainty. Perspectives make context sensitivity explicit, preventing confusion and ambiguity.

Frames : 

Frames Frames : A collection of nodes that describe a stereotyped object, act or event. Example : newspaper report.

Earthquake Example: 

Earthquake Example Killed Injured Homeless Damage Magnitude Fault Crest River Wind-speed Name Place Day Time Number-of-guests Host Age Birthday-person

Earthquake Example cont.: 

Earthquake Example cont. Earthquake Hits Lower Slabovia Today an extremely serious earthquake of magnitude 8.5 hit Lower Slabovia killing 25 people and causing $500,000,000 in damage. The president of Lower Slabovia said the hard-hit area near the Sadie Hawkins fault has been a danger zone for years.

Earthquake Example cont.: 

Earthquake Example cont. place day fatalities damage magnitude fault

Earthquake Summary Pattern: 

Earthquake Summary Pattern An earthquake occurred in value in location slot value in day slot. There were value in fatalities slot fatalities and value in damage slot in property damage. The magnitude was value in magnitude slot on the Richter scale, and the fault involved was the value in fault slot.

Instantiated Earthquake Summary Pattern: 

Instantiated Earthquake Summary Pattern An earthquake occurred in Lower Slabovia today . There were 25 fatalities and $500 million in property damage. The magnitude was 8.5 on the Richter scale, and the fault involved was the Sadie Hawkins.

Earthquake Example cont.: 

Earthquake Example cont. Earthquake Study Stopped Today, the President of Lower Slabovia killed 25 proposals totaling $500 million for research in earthquake prediction. Our Lower Slabovian correspondent calculates that 8.5 research proposals are rejected for every one approved. There are rumors that the President’s science advisor, Sadie Hawkins, is at fault.

Earthquake Example cont.: 

Earthquake Example cont. The Earthquake Study Stopped story could be summarized, naively, as though it were the story about an actual earthquake, producing the same frame as the Earthquake Hits Lower Slabovia story does.

Scripts: 

Scripts

Scripts : 

Scripts Example - Restaurant script. Script: Restaurant Roles: S=Customer Track: Coffee Shop W=Waiter Props: Tables C=Cook Menu M=Cashier F=Food O=Owner Check Money

Restaurant Example cont.: 

Restaurant Example cont. Entry conditions : S is hungry S has money Results : S has less money O has more money S is not hungry S is pleased (optional)

Restaurant Example cont.: 

Restaurant Example cont. Scene 1: Entering S PTRANS S into restaurant S ATTEND eyes to tables S MBUILD where to sit S PTRANS S to table S MOVE S to sitting position

Restaurant Example cont.: 

Restaurant Example cont. Scene 2: Ordering (menu on table) (W brings menu) (S asks for menu) S PTRANS menu to S S MTRANS signal to W S MTRANS ‘need menu’ to W W PTRANS W to table W PTRANS W to menu W PTRANS W to table W ATRANS menu to S S MTRANS W to table *S MBUILD choice of F S MTRANS signal to W W PTRANS W to table S MTRANS ‘I want F’ to W W PTRANS W to C W MTRANS (ATRANS) to C C DO (prepare F script) to Scene 3 C MTRANS ‘no F’ to W W PTRANS W to S W MTRANS ‘no F’ to S (go back to *) or (go to Scene 4 at no pay path)

Restaurant Example cont.: 

Restaurant Example cont. Scene 3 : Eating C ATRANS F to W W ATRANS F to S S INGEST F (Option : Return to Scene 2 to order more; otherwise go to Scene 4)

Restaurant Example cont.: 

Restaurant Example cont. Scene 4 : Exiting S MTRANS to W W PTRANS W to S W MOVE (write check) (W ATRANS check to S) W ATRANS check to S S ATRANS tip to W S PTRANS S to M S ATRANS money to M S PTRANS S to out of restaurant (No pay path)