Weidoing Chen and David Scott Warren. Objects as intensions. In Proceedings of the Fifth International Conference and Symposium on Logic Programming, August 1988.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....extensions of logic progremming, does not eccount for eny notion of stete. McCebe suggests thet the chenge of stete for en insrenee cen be simuleted by creeting new instences [49] Other proposeis simulete stete chenges by using assert end retract but this epproech leeks eny logicel founderion. In [33] intensionel veriebles ere introduced to keep trece of stete chenges without side effects. In other proposeis, multi heeded cleuses ere used for similer purposes. However, the notion of updeting object stete does not fit well in object oriented extensions of logic progremming. In eddition, elso ....

W. Chen and D. S. Warren. Objects as Intensions. In R.A. Kowalski and K.A. Bowen, editors, Proc. Fifth Lnt'l Conf. on Logic Programming, pages 404 419. The MIT Press, Cambridge, Mass., 1988. 31

....of logic programming, does not account for any notion of state. McCabe suggests that the change of state for an instance can be simulated by creating new instances [McC88] Other proposals simulate state changes by using assert and retract but this approach lacks any logical foundation. In [CW88] intensional variables are introduced to keep trace of state changes without side effects. In other proposals, multi headed clauses are used for similar purposes. However, the notion of updating object state does not fit well in object oriented extensions of logic programming. In addition, also ....

W. Chen and D. S. Warren. Objects as Intensions. In Proc. Fifth Int'l Conf. on Logic Programming, pages 404--419. The MIT Press, 1988.

....type structures, object are represented as typed variables. In (McCabe 1992) objects are viewed as logical theories and methods as clauses. Based on the sameidea, in (Miller 1989a) an extension of logic programming with embedded implication is used to define modules with hidden structures. In (Chen and Warren 1988), objects are viewed as non logical variables, whose value can be modify by means of an assignment construct. In (Conery 1988) objects are viewed as atomic formulas. In this approach Horn Clauses are extended to multiple headed clauses. The evolution of an object (an atomic formula) is determined ....

W. Chen and D. H. Warren. Objects as Intensions. In R. A. Kowalski and K. A. Bowen, editors, Proceedins of 5th International Conference on Logic Programming, pages 404--419. The MIT Press, Cambridge, MA, 1988.

....a foundation for object oriented ideas but update is left outside its scope. It is intended that F logic be combined with Transaction Logic to account for state change [21] An early proposal that bears some similarity to our rebinding mechanism is that of Chen and Warren using intensional logic [11]. Objects are represented by intensional variables, each such variable being mapped to an extensional state for each time point. At each point in time the past history of an object is known but its future is unknown. This provides a notion of identity separate from state, rather like our primitive ....

Weidong Chen and David Scott Warren. Objects as intensions. In Robert A. Kowalski and Kenneth A. Bowen, editors, Proceedings of the Fifth International Conference and Symposium on Logic Programming, pages 404--419. MIT Press, 1988. REFERENCES 22

....(in the form of a stream) and others for attribute values. In Conery s merger [Con88] where predicate interpretation changes during the program execution, classes are predicates, with one argument meant for an atomic object name, and others corresponding to attributes. In Objects as Intensions [CW88], an object is an individual variable, standing for the infinite list of its states during history. The concept of attribute is often understood more generally in mergers than in conventional OO (see Section 3 for details) Attribute value changes. Zaniolo s approach enables no dynamics. ESP ....

W. Chen and D. S. Warren. Objects as intensions. In Logical Programming: Proc. 5th Int'l Conf. and Symp., Seattle, Aug 1988, pp 404-19. Cambridge, MA: The MIT Press, 1988.

....In [62] McCabe suggests that the change of state for an instance can be simulated by creating new instances. Other proposals [34] simulate the changes of state by means of assert and retract but this approach lacks any logical foundation. A refined solution has been proposed by Chen and Warren in [27], where intensional variables are introduced to keep track of state changes without side effects. In other proposals [35, 66] state change is simulated by means of unification and recursion within a concurrent logic programming framework. In [3] and [28] multi headed clauses are used for similar ....

W. Chen and D.H. Warren. Objects as intensions. In R. A. Kowalski and K. A. Bowen, editors, Proc. 5th Int. Conference on Logic Programming, pages 404--419. The MIT Press, 1988.

....program clauses during the execution (see again Section ) in order to implement a notion of object with an internal update able state. The interpretation of methods as logic program clauses has also been adopted in other approaches. Objects as variables. In order to overcome this problem, in [17], Prolog was extended by considering a class of non logical variables, whose value can be modify by invoking a sort of assignment construct. Dynamic predicates, i.e. predicates that can modify the state of a variable, have a particular semantics based on Kripke like models. Their denotation is ....

W. Chen and D. H. Warren. Objects as Intensions. In R. A. Kowalski and K. A. Bowen, editors, Proceedins of 5th International Conference on Logic Programming, pages 404--419. The MIT Press, Cambridge, MA, 1988.

....the built in non logical operators assert and retract of Prolog 1 . There are many problems with assert retract which motivate e.g. Warren [149] to talk about The evils of assert and which make programming using these operators a rather non declarative effort [6] One solution is proposed in [30] has utilized an intentional semantics to describe Horn clause logic, which allows intention variables to be used in programs. Such a variable is actually a function from a state to a set of values, and also contains a sequence of states which represents the partial history of the object. The ....

Chen W., Warren D.H., Objects as intensions, Fifth International Conference on Logic Programming, Proceeding, 1988.

....and non deterministic, and it is possible not only to search for objects with certain properties but also to do hypothetical reasoning with them. 1 Introduction Many attempts have been made in recent years to extend logic programming with features found in object oriented programming languages [2,3,5,6,12,9]. Much of this work has used Prolog and Horn clause as a foundation. In this paper, we start with an enrichment of Horn clause logic that contains a natural scoping mechanism and then show how aspects of object oriented programming can be represented. Our account of state and state updates is the ....

....programming style in several directions. The question of how a class definition might redefine an inherited method will be investigated, as will changes to the current syntax to make continuation passing implicit. It is expected that this may lead to a syntax similar to the dynamic predicates of [5]. Another area of interest is how paramaterized modules might be implemented in a more efficient manner, avoiding the need to load multiple copies of a segment of code. Acknowledgements Both authors are supported in part by grants ONR N00014 88 K 0633, NSF CCR 87 05596, DARPA N00014 85 K 0018, ....

Weidong Chen and David Scott Warren. Objects as intensions. In R. Kowalski and K. Bowen, editors, Logic Programming: Proceedings of the 5th International Conference and Symposium, pages 404--419. MIT Press, 1988.

....Variables in the label are universally quantified over the whole theory. Special rules, called class rules, are used to inherit from other objects. McCabe s book [22] gives many examples of L O programs. There are many other approaches to object oriented logic programming. See for example [23, 1, 2, 11, 26, 4, 10] and the survey by Davison [12] The approach we take differs from McCabe s in several key points. The notion of object is superficially the same in both approaches but the relationship to classes is different. In L O objects are instantiations of a parametrised theory (classes are not explicitly ....

Weidong Chen and David Scott Warren. Objects as intensions. In Robert A. Kowalski and Kenneth A. Bowen, editors, Proceedings of the Fifth International Conference and Symposium on Logic Programming, pages 404--419. MIT Press, 1988.

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Weidoing Chen and David Scott Warren. Objects as intensions. In Proceedings of the Fifth International Conference and Symposium on Logic Programming, August 1988.

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