From: Harold Boley (boley@informatik.uni-kl.de)
Date: 07/22/03
Hi Mike and All, this is for today's Rules XML Syntax session (inlined and attached). Talk to you in 15 minutes, Harold ---------------------------------------------- SEMANTIC WEB RULE LANGUAGE: DATA MODEL, SYNTACTIC LAWS, AND XML MARKUP Draft 22 July 03 Harold Boley, Said Tabet, Gerd Wagner We give the rule syntax as a data model with algebraic laws in a graphical notation. For presentation purposes we begin with the positional syntax and then go into the object-oriented syntax. The algebraic laws, here tree equations, define equivalence classes that give us a higher level of abstraction than in ordinary abstract syntax. Data model trees can be easily transcribed into the XML markup. The PR shorthand and presentation syntax (http://www.ruleml.org/submission/ruleml-shortation.html), where given, can also be pasted into the parser linked from PR's 'Implementation' section. For an XML markup discussion see "Essential RuleML: The discount rulebase use case" (http://www.ruleml.org/submission/essentialruleml.html). Finally, we give an initial syntax for typing rule variables by URI-referencing RDFS or OWL classes. Positional Syntax ================= Data Model ~~~~~~~~~ Trees with two categories of arcs, XML-like positional arcs & RDF-like role arcs: Positional: | Roles (system): * Example (PR): discount(?customer,?product,percent5.0) :- premium(?customer), regular(?product). Example (normal): imp------------------------------------------------- * * head * body * * * atom---------------------------- and---------------------- * | | | * * opr * | | | * * * | | | * * rel var var ind atom---------- atom---------- . . . . * | * | . . . . opr * | opr * | . . . . * | * | discount customer product 5.0 percent rel var rel var . . . . . . . . . . . . premium customer regular product Example (expanded): imp------------------------------------------------- * * head * body * * * atom------------------ and---------------------- * * * * * seq * * * * * * * opr * ------------------- * * * | | | * * rel | | | atom---------- atom---------- . | | | * * * * . var var ind * seq * * seq * . . . . * * * * . . . . opr * - opr * - . . . . * | * | discount customer product 5.0 percent rel var rel var . . . . . . . . . . . . premium customer regular product Example (considered option: role type, multiple body): imp------------------------------------------------------------------------ * * * head * mbody * mbody * * * * atom---------------------------- * * * | | | * * opr * | | | * * * | | | * * discount var var ind atom---------- atom---------- . . . * | * | . . . opr * | opr * | . . . * | * | customer product 5.0 percent premium var regular var . . . . . . customer product Example (preferred option: role type, branching body): imp--------------------------------------------------------------- * * head * bodya * * * atom---------------------------- * * | | | ******************** opr * | | | * * * | | | * * discount var var ind atom---------- atom---------- . . . * | * | . . . opr * | opr * | . . . * | * | customer product 5.0 percent premium var regular var . . . . . . customer product Laws ~~~ Commutativity for system roles: Specific: imp------------------ imp------------------ * * * * head * body * = body * head * * * * * / x \ / y \ / y \ / x \ General: type------------------------------------- type------------------------------------- * * * * . . . rolej * . . . rolek * . . . = . . . rolek * . . . rolej * . . . * * * * / x \ / y \ / y \ / x \ Sequence expansion/contraction: Specific: atom-------------------------- atom------------------ * | | * * opr * | . . . | = opr * seq * * | | * * rel arg1 argN * ----------------- . * | | . * | . . . | . * | | pcd rel arg1 argN . . . pcd General (analogous) Role type: Specific (needed for Datalog): atom-------------------------- atom-------------------------- * | | * | | opr * | . . . | = opr * | . . . | * | | * | | rel arg1 argN pcd arg1 argN . . . pcd Specific (needed for Hornlog): cterm------------------------- cterm------------------------- * | | * | | opc * | . . . | = opc * | . . . | * | | * | | ctor arg1 argN pcd arg1 argN . . . pcd General (untyped PCDATA are regarded as being typed with 'any'): This corresponds to an RDFS-like range restriction or a description logic-like equivalence Forall rolet.type <=> Forall rolea.any . When no ambiguity arises, 'rolet' and 'rolea' can be the same, like 'opr' above type0---------------------- type0---------------------- * * . . . rolet * . . . = . . . rolea * . . . * * type pcd . . . pcd Multiple body (considered option): General (the multiple-body role 'mbody' is non-functional, like, e.g., 'author' in Dublin Core): imp--------------------- imp---------------------------------------- * * * body * = mbody * mbody * . . . * . . . . . . * * . . . and---------------------- * * * * * * * . . . * * . . . * * * * * / c1 \ / cM \ / c1 \ / cM \ Branching body (preferred option): General (the body-and role 'bodya' is syntactically functional, but has an implicit set value): imp--------------------- imp---------------------------------------- * * body * = bodya * . . . * . . . . . . * . . . and---------------------- ******************** * * * * * . . . * * . . . * * * * * / c1 \ / cM \ / c1 \ / cM \ Object-Oriented Syntax ====================== Data Model ~~~~~~~~~ Trees with two main categories and two subcategories of arcs: Positional: | Roles (system): * Roles (user): # Example (PR): discount(cust->?customer;prod->?product;rebate->percent5.0) :- premium(cust->?customer), regular(prod->?product). Example (normal): imp---------------------------------------------------- * * head * body * * * atom------------------------------- and----------------------- * # # # * * opr * cust # prod # rebate # * * * # # # * * rel var var ind atom----------- atom----------- . . . . * # * # . . . . opr * cust # opr * prod # . . . . * # * # discount customer product 5.0 percent rel var rel var . . . . . . . . . . . . premium customer regular product Example (considered option: role type, multiple body): imp---------------------------------------------------------------------------- * * * head * mbody * mbody * * * * * * * atom------------------------------- * * * # # # * * opr * cust # prod # rebate # * * * # # # * * discount var var ind atom----------- atom----------- . . . * # * # . . . opr * cust # opr * prod # . . . * # * # customer product 5.0 percent premium var regular var . . . . . . customer product Example (preferred option: role type, branching body): imp------------------------------------------------------------------ * * head * bodya * * * * * atom------------------------------- * * # # # ********************* opr * cust # prod # rebate # * * * # # # * * discount var var ind atom----------- atom----------- . . . * # * # . . . opr * cust # opr * prod # . . . * # * # customer product 5.0 percent premium var regular var . . . . . . customer product Laws ~~~ Commutativity of roles: system-system (see above) as well as user-user and system-user (analogous) The other laws are taken directly from the positional syntax Typing Syntax ============= An initial XML syntax for typing can be based on the 'Typing' section of the PR syntax (http://www.ruleml.org/submission/ruleml-shortation.html), using QNames that URI-reference RDFS or OWL classes. While typing is sketched for the positional syntax here, it can be specified in the same manner for the object-oriented syntax. Example (PR): c:='http://e-biz.org/taxonomy#Custclass'. p:='http://e-biz.org/taxonomy#Prodclass'. discount(c:?customer,p:?product,percent5.0) :- premium(c:?customer), regular(p:?product). Example (normal, with URI declarations): c:='http://e-biz.org/taxonomy#Custclass'. p:='http://e-biz.org/taxonomy#Prodclass'. imp------------------------------------------------- * * head * body * * * atom---------------------------- and---------------------- * | | | * * opr * | | | * * * | | | * * rel var var ind atom---------- atom---------- . . . . * | * | . . . . opr * | opr * | . . . . * | * | discount c:customer p:product 5.0 percent rel var rel var . . . . . . . . . . . . premium c:customer regular p:product
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