Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. The MIT Press, 1991.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....c extensions, an overview of which is given in subsection 3.3. The description that follows will base on Hassan A t Kaci s book Warren s Abstract Machine: A Tutorial Reconstruction ( AK91] while this book is out of print, an online postscript version for non commercial use can be found at [AK95] All features that hallmark the RAWAM are extensions to the WAM described therein. Along these lines, we will emphasize mainly the di erences and extensions w.r.t. to this book. Because the RAWAM is so related to the WAM, we will try to describe its implementation in such a way that it can be ....

Hassan At-Kaci. List of known bugs for the book: Hassan At-Kaci, "Warren's Abstract Machine: A Tutorial Reconstruction". http://www.isg.sfu.ca/~hak, 1995.

..... 41 C A Demo Script 42 1 INTRODUCTION 4 1 Introduction In this work we describe the C implementation of the Relfun Adapted WAM (RAWAM) This implementation arose out of the author s attempt to understand the principles of the Warren s Abstract Machine ( War83] War77] GC96] AK91] GLLO85] VR94] MW88] Rus92] It came along with the question of how to increase the speed of the LISP implemented abstract machines for our relational functional programming language, RelFun ( Bol97] The RAWAM is now the rst component of the RelFun implementation which is fully ....

....module system, a more exible realization of the standard WAM memory layout, as well as many Relfun speci c extensions, an overview of which is given in subsection 3.3. The description that follows will base on Hassan A t Kaci s book Warren s Abstract Machine: A Tutorial Reconstruction ( AK91] while this book is out of print, an online postscript version for non commercial use can be found at [AK95] All features that hallmark the RAWAM are extensions to the WAM described therein. Along these lines, we will emphasize mainly the di erences and extensions w.r.t. to this book. ....

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. The MIT Press, Cambridge, Massachusetts, 1991.

....logic. For example, even(0) even(t) succeeds exactly if 0 = t. In the second line we can unfold the uni cation further, since one of the terms to be uni ed is known to be s(s(x) This kinds of optimization naturally lead to a higher level version of the Warren Abstract Machine (WAM) [AK91] which is the basis for almost all modern Prolog compilers. 5.6 Exercises Exercise 5.1 Carefully prove the correctness of resolution (Theorem 5.3) Explicitly state and prove any generalized induction hypotheses or lemmas you might need. Exercise 5.2 We consider the new connective from ....

Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

....content is stored on the trail. To this kind of trail we refer to as single value trail. Starting exploration from a node puts a mark on the trail. Undoing the trail restores all memory locations up to the previous mark. This is essentially the technology that is used in Warren s Abstract Machine [14, 4]. In the context of trailing based constraint programming systems two further techniques come into play: Time stamping. With finite domains, for example, the domain of a variable can be narrowed multiply. However it is sufficient to trail only the original value, intermediate values need no ....

Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. Logic Programming Series. The MIT Press, Cambridge, MA, USA, 1991.

....Oz provides for multiple threads that are scheduled fairly. In Amoz threads are lightweight, implemented as multiple stacks of tasks that are scheduled preemptively and fairly. The design of abstract machines for constraint based languages has been pioneered by the Warren Abstract Machine (WAM) [25, 1]. The implementation of DFKI Oz has been influenced by the AGENTS implementation of the concurrent constraint language AKL [8] AKL is a deep guard language providing for encapsulated search. However, AKL does not provide for first class procedures and threads. cc(FD) 23] is a constraint ....

.... TUPLE(f=n) S=new Node htag:TUPLE, tuple:hlabel:f=n, args:new Node[n]ii; case PUT ARG(i,j) S tuple.args[i] E[j] case UNIFY S(i) if (unify(S,E[i] False) goto fail; The compilation scheme presented above is simplified; the integration of optimization techniques known from the WAM [25, 1, 24] like read write mode unification, and allocation of temporary variables to registers is straightforward and is not detailed. 6 Threads and Matching This section introduces threads through a restricted form of conditional expression that implements pattern matching. Conditionals considered ....

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Hassan Ait-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. Logic Programming Series. The MIT Press, Cambridge, MA, 1991.

....FD.distinct enforces all list elements to be distinct, whereas the propagators S = 0 and M = 0 enforce the variables S and M to be distinct from 0. The variables for the letters are distributed (by FD.distribute) according to a first fail strategy. Applying the search engine DFS to Money returns [[9 3 4 2 1 0 5 7]] 46 proc DFE S Commit S 1 DFE S Commit C 2 DFE C (a) Exploration. try DFE NewSpace P nil (b) Engine. Figure 5.3: Depth first search engine using exceptions. 5.2 Simplifying Control: Exceptions Depth first search for a single solution has a simple termination ....

....A of the root node N have been explored, further recomputation from N always starts with recomputing A. The optimization now is to do the recomputation step N A only once. This optimization is well known. For example, it corresponds to the trust me instruction in Warren s Abstract Machine [5]. Let us consider a complete binary search tree of height k. The rightmost path in the tree has k 1 nodes and requires k exploration steps (edges) A left subtree issuing from a node at height i on this path requires i 2 1 exploration steps (this is the unoptimized case) Altogether, a ....

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. Logic Programming Series. The MIT Press, Cambridge, MA, USA, 1991.

....uni cation. We then describe changes to the instruction set. The last part of this section illustrates the compilation model by presenting the code generated for some simple higher order programs. A familiarity with the original abstract machine of Warren, such as might be obtained from [3] or [43] is assumed in this exposition. 6.1 The Structure of the Extended Machine Figure 4 depicts the various data areas and registers present in the extended abstract machine and provides a snapshot of a machine state during computation. The code area, the heap, the local stack and the trail ....

....(list i) respectively. We note that in the only place where the unify value instruction appears in this code, there is no utility for the type argument and, observing that this instruction will never be executed in read mode, we may replace it with a special set value instruction as suggested in [3]. As a nal comment, we observe that both the proceed nish unify and the execute nish unify instructions that appear in this code are essential: depending on the form of the rst and third incoming arguments, execution of the term simpli cation code for either clause may lead to bindings ....

Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

....establishing and maintaining choice points and permitting a further indexing based on the structure of speci c arguments of the goal. We assume the reader is familiar with these ideas and we use the needed instructions below without further discussion. The uninitiated reader may consult [39] or [2] for details. The simpli cation operation within the context of each clause reduces to matching each of the arguments of the goal with the corresponding argument of the clause head. The actual arguments can be made available in WAM fashion via argument registers. As noted already, the ....

Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

....cons(cons(a; nil) L) and assuming that the de ned type of a is i and of cons is as indicated in Section 2. In this gure we have made explicit also the representation of types in the type heap. We have chosen to use here the representation used in the WAM for terms as illustrated in, e.g. [1]. Note that a compound term (structure) is represented as usual by placing the function symbol and arguments in consecutive cells on the heap. In conjunction with this gure, we observe that the depiction of the entries in Although we do not consider this aspect explicitly here, integers and ....

Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

....2, garbage collection in the WAM in Section 3, and present a short discussion on the need for garbage collection of the heap in a Prolog system with tabling in Section 4. 2 Memory organization in WAM based tabled abstract machines We assume familiarity with Prolog and the WAM [War83] see also [AK91] for a general introduction) and to some extent with tabled execution of logic programs. Also knowledge of garbage collection techniques for Prolog will help but nevertheless we review them in Section 3.1; see also [BL94, DET96] for specific instances of heap garbage collection for Prolog and ....

Hassan Ait-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. The MIT Press, Cambridge, Massachusetts, 1991. See also: http://www.isg.sfu.ca/~hak/documents/wam.html.

....by passing the binding ID between an attribute representation and an entity representation. Anyway, a vector of bits (e.g. 32 bit length) is used in the binding representation. Indirect memory reference is often used in combination, for example, using a chain of references to represent one binding [2]. This representation makes it possible to keep additiveness while retaining information of bindings. We agree that this way of the binding representation is powerful and e#cient. It is also discussed that a Otherwise a human cannot understand both two bindings at a time, e.g. John lover ....

Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. The MIT Press, 1991.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

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Hassan Ait-Kaci. Warren's abstract machine: a tutorial reconstruction. MIT Press, 1991.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. The MIT Press, 1991.

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Hassan Ait-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. The MIT Press, Cambridge, Massachusetts, 1991. 96] Harold Boley, Simone Andel, Klaus Elsbernd, Michael Herfert, Michael Sintek, and Werner Stein. RELFUN Guide: Programming with Relations and Functions Made Easy. Document D-93-12, DFKI GmbH, July 1996. Second, Revised Edition.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. The MIT Press, Cambridge, Massachusetts, 1991.

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Hassan Ait-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, Series in Logic Programming, 1991.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

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Hassan At-Kaci. Warren's Abstract Machine: A Tutorial Reconstruction. MIT Press, 1991.

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