ns2 project in Ukraine

    ns2 project in Ukraine data structures similar to those used in the network matchers are used to evaluate metarules. It is dearly an eager ns2 project in Ukraine approach, and is designed especially for distributed evaluation cases. Why might this be a better ns2 project in Ukraine approach than folding metarules into the object level system directly as outlined above since it incurs expensive instance communication overhead First, there ns2 project in Ukraine may be no choice if one is using a distributed computing environment.

     Communication is a necessity and thus separating the metarule implementation from the object level ns2 project in Ukraine implementation is more than sensible. Second, one may wish to run a different set of metarules against the same object level rules. We need not ns2 project in Ukraine recompile and reconfigure the object level system, only the metarule system. Third, as discussed in , it may be required in order for incremental update through metarules to be performed correctly. The operational semantics of PARULEL suggests a natural decomposition of overall processing into three separate phases, namely, match, redact, and fire.

     Our proposed ns2 project in Ukraine implmentation seeks to remove the separation between object-level rule matching , which produces rule instances, and the subsequent filtering of these instances using the metarules The operational semantics of PARULEL suggests a natural ns2 project in Ukraine decomposition of overall processing into three separate phases, namely, match, redact, and fire. Our proposed implmentation seeks to remove the separation between ns2 project in Ukraine object-level rule matching , which produces rule instances, and the subsequent filtering of these instances using the metarules All sites match base rules, and send resulting instances to a ns2 project in Ukrainequeue read by a single, centralized nietarule processing site.  MRP gathers all instances from all sites.

ns2 project in Turkey

      ns2 project in Turkey rather, we attempt to make all match work as relevant as possible by eliminating conflicting rule instances according to a set of ns2 project in Turkey user specified metarules. Another possible metarule implementation discussed in  is as follows. We compile the rnetarules into object level rules while rewriting the object ns2 project in Turkey level rules mentioned in the metarules. Here, the object level rules are changed so that they always fire but assert an “instance’object in the object level WM. Metarules ns2 project in Turkey match against these instance objects, and when a metarule fires, its actions are not redactions, but the RHS actions of the rules that they would have allowed to fire.

        This idea ns2 project in Turkey is rather simple and al-lows for an easy metarule implementation by using the object level rule matc,her verbatim. However, this is probably inefficient since it forces ns2 project in Turkey the object level system to execute various phases of metarule evaluation and object level evaluation alternately through the rule evaluator. Essentially the rule ns2 project in Turkey evaluator is used to simulate the metarules. We should seek more efficient implementations than this approach suggests. Rather than trying to compile metarules away in terms of the object level system, metarules might be processed as a separate body of ns2 project in Turkey  code and data structures.

      This is the approach we adopt in PARADISER, and we describe ns2 project in Turkey this approach as a “twophase” metarule processing algorithm in the next two sections. We provide both centralized and distributed versions of this method in some detail. Here the ns2 project in Turkey idea is that the object level system carries out ns2 project in Turkey its normal operation producing instances that are sent to the metarule matcher as messages.

ns2 project in France

    ns2 project in France how might it be more intelligent  Lazy tnatching works for OPS because it is possible to define a total ordering over WM elements. Match ns2 project in France runs faster since it stops searching for instances once one is found. The computed instance is guaranteed to be the same instance chosen from an eager computation. In metarule matching, one can presumably stop assoon as one instance is found too. But this is ns2 project in France not the case.

    The semantics of metarules dictates that when there are twoormore conflicting ruleinstances, some particular instance should be redacted. Can we ns2 project in France define a total ordering over rule instances and use lazy matching at the network nodes applied to instances so that only the single rule instanc,e that would be fired is ns2 project in France  generated and those that would be redacted would not even be generated? The answer is no. Preference here is not dependent upon lexicographic sort of a totally ordered ns2 project in France WM as in OPS. Preference here means programmer supplied preference based upon arbitrary conditions on bound values in instances that are dynamically computed and that, may not define a total ordering. It is unlikely that lazy match will be effective in systems ns2 project in France with set-oriented semantics as described here.

     Our goal is to compute and execute as many instances, and thus asmany working memory transactions, in a single ns2 project in France inference cycle aspossible. We do not seek to compute a single firable rule as quickly as ns2 project in France possible in a single inference cycle by reducing the amount of irrelevant match work as in lazy evaluation.

ns2 project in Germany

     ns2 project in Germany all instances might have to be comrnunicated to one site that computes the aggregate function against the set of instances. Of course, it ns2 project in Germany may be possible to compute the aggregate function in parallel among the sites if the function in question is associative and commutative. But one cannot determine ns2 project in Germany apriori what a metarule programmer might actuallyspecify .

Object level rule matching may be lazy, as in LEAPS , or eager as in PARULEL and SOAR . In the case of lazy evaluation, one would expect the matcher to produce the instances that would ns2 project in Germany be fired after metarule redactions without generating the instances that would be redacted. However, this is impractical, since for an instance to be redacted, it must be matched and bound in the LHS of a metarule and participate in conditional expressions between ns2 project in Germany other rule instances. Indeed, a single instance may participate in many different metarules and thus may be matched against a number of instances generated ns2 project in Germany  by different object-level rules.

This implies that the “redactable instances” must ns2 project in Germany  be generated and tested in the LHS of the metarule along with other rule instances. Thus, lazy evaluation is not an appropriate evaluation strategy since it seeks to generate only one instance at a time. Furthermore, for languages with set-oriented semantics, lazy ns2 project in Germany evaluation would necessarily require repeated invocation to generate a stream of instances to saturation before proceeding to fire those instances, i.e., lazy evaluation ns2 project in Germany would be a step in the most inner loop of an eager evaluation computation.

ns2 project in kuwait

    ns2 project in Kuwait it is impossible to specify control on the basis of data matched by rules, nor can one specify control ns2 project in Kuwait between instances of the same rule. PARULE’L’s metarules ameliorate these problems. In the initial definition of PARULEL, we allow conditional expressions in the LHS of metarules. These conditions ns2 project in Kuwait evaluate arithmetic expressions containing values bound in the object level rule instances. In certain cases one may want a more expressive ns2 project in Kuwait metarule that computes some arbitrary “aggregate” condition on its LHS that is applied to a set of matching base rule instances.

        For example, one may choose to fire a set of rule ns2 project in kuwait instance  if the number of those instances is greater thanthe number of instances generated ns2 project in Kuwait by another distinct object level rule. We distinguish these two cases as “base” metarules and “aggregate” metarules. Each poses different problems for metarule matching. The initial PARADISER implementation uses a replicated database ns2 project in Kuwait configuration where multiple processing sites are involved in rule evaluation. Each processing site has a distinct constrained version of the rule program.

     Metarule matching ns2 project in kuwait is complicated by the fact that instances at one site may need to be communicated to another site in order for a metarule to be matched fully. If we choose not to ns2 project in Kuwait communicate instances and do all metalevel processing at each individual site, additional burden is placed on the compile time distribution and ns2 project in Kuwait reorganization subsystem, which is also responsible for load balancing of base rule evaluations In the case of aggregate metarules, the point is moot.

ns2 project in oman

     ns2 project in oman but no further optimizations are applied, and hence no large gain in parallelism can be expected . ns2 project in oman PARULEL’s execution is intended to be optimized by way of copy-and-constraining of rules distributed to different processing sites. ns2 projects in oman Optimizations may also be applied according to rule interdependence analysis as described in . Besides the issue of parallelism, ns2 project in oman RPL provides a declarative framework for conflict resolution like that proposed for ns2 project in oman PARULEL. However, it appears that the attributes of the firing groups used for ns2 project in oman conflict resolution are hard-coded; there is no actual way of accessing the conflict set itself.

      Another system related to PARlJLEL is RDL . Although the execution ns2 project in oman semantics is defined as nondeterministic. choice for rule execution, control can bespecified separately from the rules by way of a control language based upon ns2 projects in oman regular expressions. In early work , one of the authors defined a rule language controlled by a separate control language based upon regular expressions, that specified sequential, ns2 project in oman repetitive alternative, and permutable rule executions. Although useful, the ns2 project in oman approach had a major problem in practice.

     Occasionally the control expression being followed required the executionof a rule that had no instantiations. Ultimately, ns2 project in oman  metarules were defined to resolve these “control conflicts”, which then quickly subsumed the entire regular expression language, i.e., metarules provided sufficient specification of c,ontrol. As we have noted, there is of course the problem with strict specification of control sequences by way of rule names.

ns2 project in Western Australia

      ns2 project in Western Australia the action of these metarules is to remove, or redact, one or more of the conflicting rule instances from the conflict set. The post-redaction conflict set is considered to be conflict-free, and can be fired ns2 project in Western Australia concurrently, realizing set-oriented database updates. The metarules act as an instrument for resolving inconsistencies implicit in the original rule set as ns2 project in Western Australia execution progresses. The operational semantics or conflict resolution strategies can themselves be declaratively specified, separating the logic of a program from its control.

The database of facts in PARULEL programs is provided by a relational ns2 project in Western Australia database management system, rather than the LISP ns2 project in Western Australia environment of typical AI rule languages such as OPS. Within the PARADISER environment, PARULEL rules are compiled into an intermediate form consisting of relational expressions which are processed by a runtime evaluation system that is loosely coupled ns2 project in Western Australia with the database management system.

Thus, PARULEL rules may be processed against a very large store of persistent data that is managed by the database system . The generalized operational semantics of PARULEL is captured In the first rule, PI, we wish to find the set of pairs of distinct tuples from the A relation satisfying the requirement ns2 project in Western Australia that the sum of their second attributes is bounded by a constant,In the second rule, , we find triples of tuples satisfying an analogous condition on their second attributes. Executing ns2 project in Western Australia the rule instances creates new tuples in the intensional relations, B and C, composed of the first attributes of the tuples matching one of the rules. However, notice that some individual tuple from the A relation may appear in multiple instances of either rule, or both.

ns2 project in Victoria

        ns2 project in Victoria under the FDM scheme, each metarule is assigned to a distinct processor. Thus, in a realistic situation, many of the MRPs may be inactive. We have developed protocols that detect whether or not a particular ns2 project in Victoria MRP will be active at a given cycle. It is then possible to distribute the processing load of the active MRPs over all available MRPs, i.e., we use the resources of the inactive ns2 project in Victoria MRPs whenever possible. The load distribution is based on the assumption that at each cycle, the entire conflict set is available at every MRP, since they can all collect all ns2 project in Victoria of the instances as they are broadc.ast by the BRPs.

      Load distribution then reduces to following a protocol that determines how active MRPs will claim the resources of inactive ns2 project in Victoria ones, and then executing some variant of a popular parallel join algorithm adapted to our particular needs. In future work, we plan to conduct comparative studies ns2 project in Victoria of the various approaches to distributed control as detailed in this paper with ns2 project in Victoria  actual implementations within the PARADISER architecture.

     We also intend to explore alternative and useful control specification a number ns2 project in Victoria of PARULEL programs are studied and some prelirninary ideas are presented on how to improve the expressivity of the metarule construct of PARULEL. These are important open problems that will be the focus of future work. The “programmable” conflict resolution strategy is ns2 project in Victoria realized via meta-level rules, that express domaindependent relationships among the rule instantiationsin the conflict set at any given cycle. These metarules specify what specific types of interactions among rule instances indicate a conflict.

ns2 project in Ontario

       ns2 project in Ontario however, at the same time, we must ensure that all possible instances are generated over all the sites. The above two goals may be difficult to satisfy simultaneously. Generating relevant instances according ns2 project in Ontario to the metarules may require generating more instances than in the ordinary case where we use restriction predicates that divide the range of each base rule RA according to the ns2 project in Ontario processing potential of the sites, to get match time reductions per rule and uniform completion times over all sites.

         This is so, since the distribution of relevant instances ns2 project in Ontario may not agree with that determined by the algorithm that is only concerned with dividing up the match effort over all sites. The PARADISER system is now operational with base rule processing being fully distributed and metarule processing being carried ns2 project in Ontario out at a single MRP. Initial experiments have shown that for large data sets, the BRPs perform well under dynamic load balancing to compute base rule matches in ns2 project in Ontario parallel and reduces the match time thus allowing the system to scale.

      However, the single site MRP emerges as a bot,- tleneck. We have begun work on distributing the metarule processing as well. Our current effort is to provide distributed metarule processing ns2 project in Ontario using the full distribution  scheme. Our initial experiments point to typical patterns in the behavior of a rule-based system as execution progresses. One such pattern is ns2 project in Ontario that after several cycles, only a few metarules are typically active, since many of the base rules relevant to the bulk of the metarules do not produce instances after the first few cycles.

ns2 project in Northern Territory

      ns2 project in Northern Territory all instances that remain after the global MRP processing are broadcast back  so that each BRP can execute the ns2 project in Northern Territory RHS actions. Instead of level hierarchy, a Log-level hierarchy is also possible, where P is the number of B RPs . This scheme can be implemented to exhibit, eitherns2 project in Northern Territory deterministic or non-deterministic rule execution,depending on whether instances are simply marked on redaction, but allowed to participate in further metarule matching, or they are actually deleted.

       A possible worst-case scenario is that all the work may be ns2 project in Northern Territory done at the global MRP, thus making the local MRPs sources of overhead rather than contributing to speedup of the metarule matching process. The MGR scheme is similar to the LPM scheme in that an MRP is located at each BRP. However, compile time analysis is used to determine restrictions on the base rules in such a way that instances generated locally at each BRP are only those that are mutually relevant with respect to the matching of the metarules. Of course, one must also guarantee completeness, all instances must be generated over all BRPs. Recall that the match effort for base rules is distributed by heuristically choosing a restriction attribute for each rule.

      A restriction predicate on the RA restricts the match effort per rule at each base rule processing site, thereby distributing the work done in base ns2 project in Northern Territory rule matching. To achieve this, the metarules are analyzed at compile time to determine the restrictions on base rules as follows. Base rule RAs are chosen so that at each site, only those instances are generated that are relevant to each other with respect to the set of metarules.