## On the expressiveness of forwarding in higher-order communication (2009)

Venue: | In: Proc. of ICTAC. Volume 5684 of Lecture Notes in Computer Science |

Citations: | 4 - 4 self |

### BibTeX

@INPROCEEDINGS{Giusto09onthe,

author = {Cinzia Di Giusto and Jorge A. Pérez and Gianluigi Zavattaro},

title = {On the expressiveness of forwarding in higher-order communication},

booktitle = {In: Proc. of ICTAC. Volume 5684 of Lecture Notes in Computer Science},

year = {2009},

pages = {155--169},

publisher = {Springer}

}

### OpenURL

### Abstract

Abstract. In higher-order process calculi the values exchanged in communications may contain processes. There are only two capabilities for received processes: execution and forwarding. Here we propose a limited form of forwarding: output actions can only communicate the parallel composition of statically known closed processes and processes received through previously executed input actions. We study the expressiveness of a higher-order process calculus featuring this style of communication. Our main result shows that in this calculus termination is decidable while convergence is undecidable. 1

### Citations

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Citation Context ...t difficult to establish a more detailed comparison. Also similar in spirit to our work, but in a slightly different context, are some studies on the expressiveness (of fragments) of Ambient calculus =-=[14]-=-. Ambient calculi are related to higher-order calculi in that both allow the communication of objects with complex structure. Some works on the expressiveness of fragments of Ambient calculi are simil... |

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Citation Context ...ion system with strong compatibility, decidable ≤ and computable Succ. Then the existence of an infinite computation starting from a state s ∈ S is decidable. We will also need a result due to Higman =-=[11]-=- which allows to extend a well-quasiorder from a set S to the set of the finite sequences on S. To be more precise, given a set S let use denote by S ∗ the set of finite sequences built by using eleme... |

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Citation Context ...troduction Higher-order process calculi are calculi in which processes can be communicated. They have been put forward in the early 1990s, with CHOCS [1], Plain CHOCS [2], the Higher-Order π-calculus =-=[3]-=-, and others. Higher-order (or process-passing) concurrency is often presented as an alternative paradigm to the first order (or name-passing) concurrency of the π-calculus for the description of mobi... |

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Citation Context ...xhibiting an encoding of Minsky machines. 2. In sharp contrast with HOCORE, termination in HO −f is decidable. This result is obtained by appealing to the theory of well-structured transition systems =-=[8]-=-, following the approach used in [9]. As for (1), it is worth commenting that the encoding is not faithful in the sense that, unlike the encoding of Minsky machines in HOCORE, it may introduce computa... |

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Citation Context ...er examples include proof-carrying code [6] and communication of obfuscated code 1 Termination and convergence are sometimes also referred to as universal and existential termination, respectively. 2=-=[7]-=-. The former features communication of executable code that comes with a certificate: a recipient can only check the certificate and decide whether to execute the code or not. The latter consists in t... |

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Citation Context ...s decidable while convergence is undecidable. 1 Introduction Higher-order process calculi are calculi in which processes can be communicated. They have been put forward in the early 1990s, with CHOCS =-=[1]-=-, Plain CHOCS [2], the Higher-Order π-calculus [3], and others. Higher-order (or process-passing) concurrency is often presented as an alternative paradigm to the first order (or name-passing) concurr... |

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Citation Context ... convergence is undecidable. 1 Introduction Higher-order process calculi are calculi in which processes can be communicated. They have been put forward in the early 1990s, with CHOCS [1], Plain CHOCS =-=[2]-=-, the Higher-Order π-calculus [3], and others. Higher-order (or process-passing) concurrency is often presented as an alternative paradigm to the first order (or name-passing) concurrency of the π-cal... |

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Citation Context ... The simplest example is perhaps mobility of already compiled code, on which it is not possible to apply inverse translations (such as reverse engineering). Other examples include proof-carrying code =-=[6]-=- and communication of obfuscated code 1 Termination and convergence are sometimes also referred to as universal and existential termination, respectively. 2[7]. The former features communication of e... |

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Citation Context ... along the paper. We do not know of other works that study the expressiveness of higherorder calculi by restricting higher-order outputs. The recent work [13] studies finitecontrol fragments of Homer =-=[14]-=-, a higher-order process calculus with locations. While we have focused on decidability of termination and convergence, in [13] the interest is in decidability of barbed bisimilarity. One of the appro... |

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Citation Context ...to higher-order calculi in that both allow the communication of objects with complex structure. Some works on the expressiveness of fragments of Ambient calculi are similar to ours. In particular, in =-=[15]-=- it is determined that, for calculi without restric14tion (as HO −f and HOCORE), when the capability of ambient movement is ruled out from the language process termination is decidable for the fragme... |

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Citation Context ...he instantiation of a variable with a term, which is then copied as many times as there are occurrences of the variable. HOCORE is a core calculus for higher-order concurrency, recently introduced in =-=[4]-=-. It is minimal, in that only the operators strictly necessary to obtain higher-order communications are retained. This way, continuations following output messages have been left out, so communicatio... |

7 | On the Expressive Power of Recursion, Replication, and Iteration in Process Calculi. Technical report available at: http://cs.unibo.it/∼zavattar/papers.html [BF04 - Busi, Gabbrielli, et al. - 2004 |

2 | On the Expressive Power of Process Interruption and Compensation. Technical report available at: http://cs.unibo.it/∼zavattar/papers.html UBLCS-2008-15 22
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Citation Context ...siveness issue also arises. Indeed, our encoding of Minsky machines into HO −f is not faithful, which reveals a difference on the criteria each encoding satisfies. This reminds us of the situation in =-=[12]-=-, where faithful and unfaithful encodings of Turing complete formalisms into calculi with interruption and compensation are compared. Using the terminology in [12], we can say that the presented encod... |

2 |
Decidable fragments of a higher order calculus with locations
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(Show Context)
Citation Context ...lated work is [4], which was already discussed along the paper. We do not know of other works that study the expressiveness of higherorder calculi by restricting higher-order outputs. The recent work =-=[13]-=- studies finitecontrol fragments of Homer (a higher-order process calculus with locations). While we have focused on decidability of termination and convergence, the interest in [13] is on the decidab... |

1 |
On the Expressiveness of Forwarding in Higher-Order Communication (Extended Version) (2009) Available at http://www.cs. unibo.it/~perez/hocore
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(Show Context)
Citation Context ...idability of termination is addressed in Section 4. Some final remarks, as well as a review of related work, are included in Section 5. We omit most proofs; these can be found in the extended version =-=[10]-=-. 2 The Calculus We now introduce the syntax and semantics of HO −f . We use a, b, c to range over names, and x, y, z to range over variables; the sets of names and variables are disjoint. P, Q ::= a〈... |