- From: Paula-Lavinia Patranjan <paula.patranjan@ifi.lmu.de>
- Date: Tue, 23 May 2006 10:13:44 +0200
- To: public-rif-wg@w3.org
- Message-ID: <4472C438.3070909@ifi.lmu.de>
Hi, This email contains the analysis of Xcerpt and XChange following the RIFRAF criteria; like Axel, I followed Hassan's scheme. This is a response to the action recorded as http://www.w3.org/2005/rules/wg/track/actions/17 Regards, Paula --------------------------------------------------------------------------------- Authors of this analysis: Michael Eckert, Paula-Lavinia Patranjan (REWERSE) Xcerpt and XChange: Short description Xcerpt (http://www.xcerpt.org) and XChange (http://www.pms.ifi.lmu.de/projekte/xchange/) are research languages developed at the Institute for Informatics, University of Munich, by following the logic programming paradigm. Xcerpt is a Web query language developed primarily for XML data, but supports also querying RDF data. An Xcerpt program is a set of deductive rules querying data and constructing new data. XChange is a Web reactive language working primarily on XML data. An XChange program is a set of ECA rules specifying the desired reactive behaviour and Xcerpt deductive rules for constructing views over XML data (views' data can be queried in the condition part of ECA rules). Classification of Xcerpt and XChange ===== SYN: SYNTACTIC DISCRIMINATORS ===== SYN.1. RESTRICTED VS. UNRESTRICTED USE OF LOGIC VARIABLES SYN.1.1. SINGLE OCCURRENCE VS. MULTIPLE OCCURRENCE (IMPLICIT VARIABLE EQUALITY) [Xcerpt] multiple occurrence [XChange] multiple occurrence SYN.1.2. RANGE-RESTRICTED RULES (NO HEAD-ONLY VARIABLES) VS. NON-RANGE-RESTRICTED RULES [Xcerpt] range-restricted [XChange] range-restricted SYN.1.3. (FURTHER RESTRICTIONS FROM STATIC ANALYSIS RESEARCH) [Xcerpt] stratifiable SYN.2. PREDICATE VARIABLES PERMITTED VS. NOT PERMITTED * SECOND-ORDER SYNTACTIC SUGAR ALLOWING VARIABLES IN PREDICATE POSITIONS OF QUERIES OR RULE BODIES AND POSSIBLY RULE HEADS (FURTHER GENERALIZED TO FUNCTION AND EVEN ATOM POSITIONS IN [HTTP://WWW.W3.ORG/SUBMISSION/SWSF-SWSL/#SWSL-RULES-HILOG]) [Xcerpt] no [XChange] no SYN.3. MONOTONIC LLOYD-TOPOR EXTENSIONS ALLOWED VS. NOT ALLOWED * SYNTACTIC SUGAR FOR EXTENDING HORN LOGIC WITH DISJUNCTION IN RULE BODIES AS WELL AS CONJUNCTION AND CLASSICAL IMPLICATION IN RULE HEADS [HTTP://WWW.W3.ORG/SUBMISSION/SWSF-SWSL/#SWSL-RULES-MON-LT] [Xcerpt] only disjunction in rule bodies; note that when grouping constructs are used in the head, disjunction cannot rewritten into separate rules (example: f[all X] <- g[X] v h[X] is not equivalent to f[all X] <- g[X], f[all X] <- h[X]) [XChange] only disjunction in the condition part of ECA rules; the same note as above SYN.4. EXPLICIT VS. IMPLICIT RULE SCOPE * ALLOWING FORMULAS AND/OR NAMES DENOTING WHAT HAS BEEN CALLED MODULES, CONTEXTS, RULESETS, OR MODELS [HTTP://WWW.ISI.EDU/~ARGOS/MATTHEW/TRIPLE_BY_EXAMPLE.HTML] [Xcerpt] implicit rule scope [XChange] implicit rule scope SYN.4.1. SLOTTED (KEYED, ROLE-NAMED) VS. POSITIONAL ARGUMENTS * ALLOWING N-ARY ATOMS WITH A SET OF N 'ATTRIBUTE=VALUE' PAIRS AS IN RDF/OWL PROPERTIES, F-LOGIC METHODS, AND OBJECT-ORIENTED SYSTEMS [HTTP://WWW.RULEML.ORG/INDOO] [Xcerpt] positional arguments tailored to semistructured data, slotted as part of data schema possible [XChange] positional arguments tailored to semistructured data, slotted as part of data schema possible SYN.5. WEBIZED VS. NON-WEBIZED NAMES * ALLOWING URIS AS OIDS FOR CONSTANTS, FUNCTIONS, SLOTS, PREDICATES, CLASSES, AND/OR LABELS [HTTP://WWW.W3.ORG/2000/10/SWAP/PRIMER.HTML] [Xcerpt] namespaces, RDF triples [XChange] namespaces, RDF triples ===== SES: SYNTACTIC-ENTAILING-SEMANTIC DISCRIMINATORS ===== SES.1. HOMOGENEOUS (BODY HAS SINGLE EXPRESSIVENESS CLASS) VS. HYBRID (BODY HAS TWO EXPRESSIVENESS CLASSES) RULES [Xcerpt] homogeneous [XChange] homogeneous SES.2. FACT-ONLY (DATABASE TABLES) VS. RULE-ONLY VS. FACT-AND-RULE BASES [Xcerpt] fact-and-rule bases [XChange] fact-and-rule bases SES.2.1. VARIABLE-FUL (NON-GROUND) VS. VARIABLE-FREE (GROUND) FACTS (ALSO UNDER "VARIABLE-FUL VS. ... CLAUSES") [Xcerpt] variable-free facts [XChange] variable-free facts SES.3. FUNCTION-FUL (FO HORN LOGIC) VS. FUNCTION-FREE (FO DATALOG) [Xcerpt] function-like term structures, non-standard unification [XChange] function-like term structures, non-standard unification SES.3.1. FUNCTION ARITY/ARITIES [Xcerpt] n-ary [XChange] n-ary SES.3.2. FIXED VS. UNFIXED FUNCTION NESTING DEPTH [Xcerpt] unfixed [XChange] unifixed SES.3.3. UNINTERPRETED VS. INTERPRETED FUNCTIONS [Xcerpt] uninterpreted in body of rules, aggregation functions are interpreted in the head [XChange] uninterpreted in the condition part and event part of rules, aggregation functions are interpreted in the action part SES.4. VARIABLE-FUL (NON-GROUND) VS. VARIABLE-FREE (GROUND) CLAUSES [Xcerpt] variable-ful clauses [XChange] variable-ful clauses SES.4.1. VARIABLE-FUL (NON-GROUND) VS. VARIABLE-FREE (GROUND) FACTS (ALSO UNDER "FACT-ONLY ... BASES") [Xcerpt] variable-free facts [XChange] variable-free facts SES.5. PREDICATE ARITY/ARITIES [Xcerpt] n-ary [XChange] n-ary SES.6. NUMBER OF PREMISES IN RULES [Xcerpt] unrestricted [XChange] unrestricted SES.7. LABELED (ANCHORED, OIDED) VS. UNLABELED CLAUSES SES.7.1. LABELS ALLOWED VS. NOT ALLOWED AS ARGUMENTS OF USER PREDICATES [Xcerpt] no support here [XChange] no support here SES.7.2. LABELS ALLOWED VS. NOT ALLOWED AS ARGUMENTS OF PRIORITY-GIVING SYSTEM PREDICATE 'OVERRIDES' (CF. SCLP) [Xcerpt] no support here [XChange] no support here SES.8. CERTAIN VS. UNCERTAIN CLAUSES AND ATOMS [Xcerpt] certain [XChange] certain ===== SEM: SEMANTIC DISCRIMINATORS ===== SEM.1. TERMINATING (ALL QUERIES TERMINATE) VS. NON-TERMINATING (AT LEAST ONE QUERY DOES NOT TERMINATE) RULEBASES [Xcerpt] non-terminating in some recursive cases [XChange] reactive programs should not terminate, it might be the case that some rules are non-terminating (via Xcerpt) SEM.2. FINITE-MODEL VS. INFINITE-MODEL RULEBASES (CF. DECIDABILITY) [Xcerpt] infinite model [XChange] infinite model for constructed data, finite model for events SEM.3. MODALITY/INTENTIONALITY (BEYOND FOL) [Xcerpt] no support [XChange] no support ===== PRAG: PRAGMATIC DISCRIMINATORS ===== PRAG.1. INFERENCE CONTROL PRAG.1.1. FORWARD CHAINING VS. BACKWARD CHAINING VS. BIDIRECTIONAL CHAINING [Xcerpt] both are possible, backward chaining implemented [XChange] not applicable, event part forward chaining (for composite events incremental over time) and condition part backward chaining PRAG.1.2. INCREMENTAL VS. EXHAUSTIVE [Xcerpt] exhaustive [XChange] incremental PRAG.2. COMPLEXITY [Xcerpt] undecidable, complexity classes for language restrictions are investigated (e.g. conjunctive tree and graph queries) [XChange] undecidable PRAG.3. INTEROPERABILITY PRAG.3.1. ANNOTATIONS (INCLUDING CONTROLLED ENGLISH) [Xcerpt] no [XChange] no PRAG.3.2. TEST CASES [Xcerpt] XQuery use cases implemented in Xcerpt [XChange] use cases: distributed reactive Web portals with update propagation (implemented), (part of) EU-Rent case study (under development) PRAG.3.3. MAPPINGS [Xcerpt] mapping to XQuery [XChange] no
Received on Tuesday, 23 May 2006 08:14:03 UTC