Rule based systems in Games

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1 Rule based systems in Games

2 Idea Objects: scenery, objects, pesons Actions Rules

3 RC++ [Ian Wright, James Marshall - RC++: a rule-based language for game AI, 1st International Conference on Intelligent Games and Simulation (GAME-ON 2000)] a full-featured, rule-based extension to C++, designed for Sony Computer Entertainment s PlayStation2 hardware designed to facilitate the rapid creation of game AI: Describe the behavior inside game AI easy scripting of high volumes of predetermined or logic- based events for game characters to perform

4 RC++ includes: Rule language Rule language compiler Runtime executor RC++ compiler steps

5 Program ruleset containing: A collection of assertions declare type of data from working memory Assertions declaring the initial state rules

6 Example: a simple agent that moves towards its friends and tries to kiss them; who he kissed and how many times RULESET Agent [ SENSE CLASS [Sense ^Name LABEL ^Location NUMBER] ACTION CLASS [Kiss ^Name LABEL] CLASS [Friend ^Name LABEL] CLASS [Kissed ^Name LABEL ^Times NUMBER] [ // Initial ruleset WM state here //... for example: [Friend ^Name Sally] ] // Rules within ruleset specified here... ]

7 Agent rule RULE KissMyFriendsWhenClose a = [Sense ^Name?name ^Location?location] [Friend ^Name?name] WHERE [AgentClass::GetMyLocation() ==?location] b = [Kissed ^Name?name ^Times?times] -> ADD [Kiss ^Name?name] DO [?times =?times + 1] MODIFY b [Kissed ^Times?times] DELETE a ENDRULE

8 C++ code // Agent C++ class declaration for kissing agent class AgentClass: public RCAgentClass // inherits from abstract RC++ agent class { public: AgentClass(void); RCValueType GetMyLocation(void) const; KissHandler($HANDLER AgentClass::Kiss$); void Execute(void); private: // Run the agent // Agent data and pointer to ruleset instantiation }; -Agent constructor instantiates the rule - program from the op-code data -Declares C++ handlers and utilities to rule program -utility function referenced by rule void - handler function that is invoked when the corresponding ACTION class is added

9 mimosa Reference: L.Hall, A.Gordon, R. James, L. Newall A Lightweight Rule-Based AI Engine for Mobile Games, ACE 2004 MADE = Mimosa Application Development Environment MME = Mimosa Execution Evironments IDE mimosa Written in Java rules + facts Diff. progr. lang. Diff. devices Implements Rete alg.

10 Mimosa language Assertions: Define data structures: ( literalize <name> (:type field)+ ) Example: (literalize player :string name :string sex :integer age) Create instance: Example: (make player ^name jim ^sex male ^age 55) Rules (Production rules) (p <production rule name> <pattern1>... <patternn> <action1>... <actionn>) (p mb1 (goal ^g-status active ^g-type holds ^g-obj [w]) (object ^o-name [w] ^o-at [l] ^o-on ceiling) (make goal ^g-status active ^g-type move ^g-obj ladder ^g-to [l]))

11 Example: Texas Hold em Poker (p getoutnopairnodraw (hand ^playersleft [nplayers]) (goal ^arg1 actpostflop ^arg2 [x] ^status <> done) (player ^seat [x] ^hasfolded false ^besthandpostflop < 2 ^card2rank < 13 ^flushdraw < 4 ^straightdrawcards < 4) (modify 1 ^playersleft (minus [nplayers] 1)) (modify 3 ^actedpostflop yes ^hasfolded true) (modify 2 ^status done) (sendgamestatusmessage [x] fold)) External function if a player has less than a pair after the flop (where three community cards, which all players can incorporate into their hand, are revealed), they have no aces or kings, and they have no realistic prospect of drawing to a flush (seeing cards to give them five cards in the same suit) or a straight (five consecutively numbered cards) then they should fold their hand.

12 Interactive Fiction References: Inform 7 (I7) tool for creating interactive fiction (text adventure games) Consists of: virtual machine, a language called ZIL, a compiler for the language, a parser library written in the language see [1] Play example [3] [1] [2] [3]

13 Semantic Web Rule Languages

14 OWL - Web Ontology Language Ontology language for web Agenda: 1. What is an ontology? 2. OWLs? 3. Tool / browser Protégé

15 Ontology Def: An ontology is an explicit specification of a conceptualization [Tom Gruber, A Translation Approach to Portable Ontology Specifications] capture knowledge about a certain domain of interest describes: the concepts in the domain the relationships between concepts

16 OWL ontology 3 constructs: Individuals: objects in the domain / instances / instances of classes Properties: are binary relations on individuals May be: transitive, symetric, single valued (i.e. functional), have inverse Classes: Sets of individuals described using formal (mathematical) descriptions for requirements corresp. to membership of the class

17 OWL Language OWL 2004 OWL W3C OWL Working Group 3 variants of OWL, with different levels of expressiveness: vowl Lite: Supports classification hierarchy and simple constraints Simplest version vowl DL : DL = decision logic Provides: computational completeness, decidability and the availability of practical reasoning algorithms vowl Full: based on a different semantics preserve some compatibility with RDF Schema is undecidable

18 Root Element <Ontology name = xsd:anyuri > Content: (VersionInfo PriorVersion BackwardCompatibleWith IncompatibleWith Imports Annotation Class [axiom] EnumeratedClass (D,F) SubClassOf (D,F) EquivalentClasses DisjointClasses (D,F) DatatypeProperty ObjectProperty SubPropertyOf EquivalentProperties Individual [axiom] SameIndividual DifferentIndividuals)* </Ontology>

19 Protégé Goal: build simple and complex ontology-based applications free, open source collaborative ontology development environment for the Web features: Support for editing OWL 2 ontologies A default simple editing interface, which provides access to commonly used OWL constructs Full change tracking and revision history Collaboration tools such as, sharing and permissions, threaded notes and discussions, watches and notifications Customizable user interface Customizable Web forms for application/domain specific editing Support for editing OBO ontologies Multiple formats for upload and download of ontologies (supported formats: RDF/XML, Turtle, OWL/XML, OBO, and others)

20 WebProtégé Try Examples

21 Semantic Web Rule Language (SWRL) used to express rules as well as logic, combining OWL DL or OWL Lite with a subset of the Rule Markup Language Example: hasparent(?x1,?x2) hasbrother(?x2,?x3) hasuncle(?x1,?x3) <ruleml:imp> <ruleml:_rlab ruleml:href="#example1"/> <ruleml:_body> <swrlx:individualpropertyatom swrlx:property="hasparent"> <ruleml:var>x1</ruleml:var> <ruleml:var>x2</ruleml:var> </swrlx:individualpropertyatom> <swrlx:individualpropertyatom swrlx:property="hasbrother"> <ruleml:var>x2</ruleml:var> <ruleml:var>x3</ruleml:var> </swrlx:individualpropertyatom> </ruleml:_body> <ruleml:_head> <swrlx:individualpropertyatom swrlx:property="hasuncle"> <ruleml:var>x1</ruleml:var> <ruleml:var>x3</ruleml:var> </swrlx:individualpropertyatom> </ruleml:_head> </ruleml:imp>

22 Abstract Syntax axiom ::= rule rule ::= 'Implies(' [ URIreference ] { annotation } antecedent consequent ')' antecedent ::= 'Antecedent(' { atom } ')' consequent ::= 'Consequent(' { atom } ')' atom ::= description '(' i-object ')' datarange '(' d-object ')' individualvaluedpropertyid '(' i-object i-object ')' datavaluedpropertyid '(' i-object d-object ')' sameas '(' i-object i-object ')' differentfrom '(' i-object i-object ')' builtin '(' builtinid { d-object } ')' builtinid ::= URIreference... Human Readable Syntax antecedent consequent

23 RuleML

Limitations of the WWW

Limitations of the WWW A Semantic Web Application for the Air Tasking Order (ATO) ICCRTS Jun 13 2005 2:30-3:00 Albert Frantz, Milvio Franco In-house Program Air Force Research Laboratory AFRL/IFSA Rome NY Mentor: Prof. Bart