THE EFFECT OF SPACING OF VETIVER GRASS (CHRYSOPOGON ZIZANIOIDES) HEDGEROWS ON HILLSLOPE EROSION IN EASTERN REGION, GHANA

Soil erosion in Ghana negatively effects many small holder farmers due to heavy rainfall, continuous land use, and a changing climate. Inexpensive, local, and sustainable practices that can be used to reduce soil movement thus building productive soils would benefit farmers in Ghana. Vetiver grass (Chrysopogon zizanioides) has been used to this effect worldwide. Its local availability and positive reputation leaves desire to learn about its applicability in Ghana. A field study was conducted on plots of sloping farmland (10ft by 60ft) with three treatments: (1) control with no vetiver grass, (2) two vetiver grass hedgerows, (3) four vetiver grass hedgerows. Erosion pins were placed in a grid and measured periodically during the approximate 6-month study period along with daily rainfall measurements. ANOVA analysis showed small trends that the vetiver hedgerows were helping to curb erosion, although no statically significant results existed between the treatments. This hints that the grass will be effective after a greater establishment period but did not have a significant effect during the first months of its growth

Reversing Single Sessions

Session-based communication has gained a widespread acceptance in practice as a means for developing safe communicating systems via structured interactions. In this paper, we investigate how these structured interactions are affected by reversibility, which provides a computational model allowing executed interactions to be undone. In particular, we provide a systematic study of the integration of different notions of reversibility in both binary and multiparty single sessions. The considered forms of reversibility are: one for completely reversing a given session with one backward step, and another for also restoring any intermediate state of the session with either one backward step or multiple ones. We analyse the costs of reversing a session in all these different settings. Our results show that extending binary single sessions to multiparty ones does not affect the reversibility machinery and its costs

Implementing Session Centered Calculi

Recently, specific attention has been devoted to the development of service oriented process calculi. Besides the foundational aspects, it is also interesting to have prototype implementations for them in order to assess usability and to minimize the gap between theory and practice. Typically, these implementations are done in Java taking advantage of its mechanisms supporting network applications. However, most of the recurrent features of service oriented applications are re-implemented from scratch. In this paper we show how to implement a service oriented calculus, CaSPiS (Calculus of Services with Pipelines and Sessions) using the Java framework IMC, where recurrent mechanisms for network applications are already provided. By using the session oriented and pattern matching communication mechanisms provided by IMC, it is relatively simple to implement in Java all CaSPiS abstractions and thus to easily write the implementation in Java of a CaSPiS process

ReverCSP: Time-Travelling in CSP Computations

[EN] This paper presents reverCSP, a tool to animate both forward and backward CSP computations. This ability to reverse computations can be done step by step or backtracking to a given desired state of interest. reverCSP allows us to reverse computations exactly in the same order in which they happened, or also in a causally-consistent way. Therefore, reverCSP is a tool that can be especially useful to comprehend, analyze, and debug computations. reverCSP is an open-source project publicly available for the community. We describe the tool and its functionality, and we provide implementation details so that it can be reimplemented for other languages.This work has been partially supported by the EU (FEDER) and the Spanish MCI/AEI under grants TIN2016-76843-C4-1-R and PID2019- 104735RB-C41, and by the Generalitat Valenciana under grant Prometeo/2019/098 (DeepTrust).Galindo-Jiménez, CS.; Nishida, N.; Silva, J.; Tamarit, S. (2020). ReverCSP: Time-Travelling in CSP Computations. Springer. 239-245. https://doi.org/10.1007/978-3-030-52482-1_14S239245Bernadet, A., Lanese, I.: A modular formalization of reversibility for concurrent models and languages. In: Proceedings of ICE 2016, EPTCS (2016)Brown, G., Sabry, A.: Reversible communicating processes. Electron. Proc. Theor. Comput. Sci. 203, 45–59 (2016)Conserva Filhoa, M., Oliveira, M., Sampaio, A., Cavalcanti, A.: Compositional and local livelock analysis for CSP. Inf. Process. Lett 133, 21–25 (2018)Danos, V., Krivine, J.: Reversible communicating systems. In: Gardner, P., Yoshida, N. (eds.) CONCUR 2004. LNCS, vol. 3170, pp. 292–307. Springer, Heidelberg (2004). https://doi.org/10.1007/978-3-540-28644-8_19Elnozahy, E.N.M., Alvisi, L., Wang, Y.-M., Johnson, D.B.: A survey of rollback- recovery protocols in message-passing systems. ACM Comput. Surv. 34(3), 375–408 (2002)Fang, Y., Zhu, H., Zeyda, F., Fei, Y.: Modeling and analysis of the disruptor framework in csp. In: Proceedings of CCWC 2018. IEEE Computer Society (2018)Ladkin, P.B., Simons, B.B.: Static deadlock analysis for CSP-type communications. In: Fussell, D.S., Malek, M. (eds.) Responsive Computer Systems: Steps Toward Fault-Tolerant Real-Time Systems. The Springer International Series in Engineering and Computer Science, vol. 297, pp. 89–102. Springer, Boston (1995). https://doi.org/10.1007/978-1-4615-2271-3_5Landauer, R.: Irreversibility and heat generation in the computing process. IBM J. Res. Dev. 5, 183–191 (1961)Lanese, I., Antares Mezzina, C., Tiezzi, F.: Causal-consistent reversibility. Bull. EATCS 114, 17 (2014)Lanese, I., Nishida, N., Palacios, A., Vidal, G.: CauDEr: a causal-consistent reversible debugger for erlang. In: Gallagher, J.P., Sulzmann, M. (eds.) FLOPS 2018. LNCS, vol. 10818, pp. 247–263. Springer, Cham (2018). https://doi.org/10.1007/978-3-319-90686-7_16Lanese, I., Palacios, A., Vidal, G.: Causal-consistent replay debugging for message passing programs. In: Pérez, J.A., Yoshida, N. (eds.) FORTE 2019. LNCS, vol. 11535, pp. 167–184. Springer, Cham (2019). https://doi.org/10.1007/978-3-030-21759-4_10Llorens, M., Oliver, J., Silva, J., Tamarit, S.: Dynamic slicing of concurrent specification languages. Parallel Comput. 53, 1–22 (2016)Llorens, M., Oliver, J., Silva, J., Tamarit, S.: Tracking CSP computations. J. Log. Algebr. Meth. Program. 102, 138–175 (2019)Perera, R., Garg, D., Cheney, J.: Causally consistent dynamic slicing. In Proceedings of CONCUR 2016, LIPIcs, vol. 59, pp. 18:1–18:15 (2016)Phillips, I., Ulidowski, I., Yuen, S.: A reversible process calculus and the modelling of the ERK signalling pathway. In: Glück, R., Yokoyama, T. (eds.) RC 2012. LNCS, vol. 7581, pp. 218–232. Springer, Heidelberg (2013). https://doi.org/10.1007/978-3-642-36315-3_18Roscoe, A.W.: The Theory and Practice of Concurrency. Prentice Hall PTR, Upper Saddle River (1997)Zhao, H., Zhu, H., Yucheng, F., Xiao, L.: Modeling and verifying storm using CSP. In: Proceedings of HASE 2019. IEEE Computer Society (2019

On Observing Dynamic Prioritised Actions in SOC

We study the impact on observational semantics for SOC of priority mechanisms which combine dynamic priority with local pre-emption. We define manageable notions of strong and weak labelled bisimilarities for COWS, a process calculus for SOC, and provide alternative characterisations in terms of open barbed bisimilarities. These semantics show that COWS’s priority mechanisms partially recover the capability to observe receive actions (that could not be observed in a purely asynchronous setting) and that high priority primitives for termination impose specific conditions on the bisimilarities

A Process Calculus for Dynamic Networks

In this paper we propose a process calculus framework for dynamic networks in which the network topology may change as computation proceeds. The proposed calculus allows one to abstract away from neighborhood-discovery computations and it contains features for broadcasting at multiple transmission ranges and for viewing networks at different levels of abstraction. We develop a theory of confluence for the calculus and we use the machinery developed towards the verification of a leader-election algorithm for mobile ad hoc networks

AIOCJ: A Choreographic Framework for Safe Adaptive Distributed Applications

We present AIOCJ, a framework for programming distributed adaptive applications. Applications are programmed using AIOC, a choreographic language suited for expressing patterns of interaction from a global point of view. AIOC allows the programmer to specify which parts of the application can be adapted. Adaptation takes place at runtime by means of rules, which can change during the execution to tackle possibly unforeseen adaptation needs. AIOCJ relies on a solid theory that ensures applications to be deadlock-free by construction also after adaptation. We describe the architecture of AIOCJ, the design of the AIOC language, and an empirical validation of the framework.Comment: Technical Repor

Reversible Computations in Logic Programming

[EN] In this work, we say that a computation is reversible if one can find a procedure to undo the steps of a standard (or forward) computation in a deterministic way. While logic programs are often invertible (e.g., one can use the same predicate for adding and for subtracting natural numbers), computations are not reversible in the above sense. In this paper, we present a so-called Landauer embedding for SLD resolution, the operational principle of logic programs, so that it becomes reversible. A proof-of-concept implementation of a reversible debugger for Prolog that follows the ideas in this paper has been developed and is publicly available.This work is partially supported by the EU (FEDER) and the Spanish MCI/AEI under grants TIN2016-76843-C4-1-R/PID2019-104735RB-C41, by the Generalitat Valenciana under grant Prometeo/2019/098 (DeepTrust), and by the COST Action IC1405 on Reversible Computation - extending horizons of computing.Vidal, G. (2020). Reversible Computations in Logic Programming. Springer. 246-254. https://doi.org/10.1007/978-3-030-52482-1_15S246254Apt, K.: From Logic Programming to Prolog. Prentice Hall, Upper Saddle River (1997)Ducassé, M.: Opium: an extendable trace analyzer for prolog. J. Log. Program. 39(1–3), 177–223 (1999). https://doi.org/10.1016/S0743-1066(98)10036-5Landauer, R.: Irreversibility and heat generation in the computing process. IBM J. Res. Dev. 5, 183–191 (1961)Lanese, I., Palacios, A., Vidal, G.: Causal-consistent replay debugging for message passing programs. In: Pérez, J.A., Yoshida, N. (eds.) FORTE 2019. LNCS, vol. 11535, pp. 167–184. Springer, Cham (2019). https://doi.org/10.1007/978-3-030-21759-4_10Lloyd, J.: Foundations of Logic Programming, 2nd edn. Springer, Berlin (1987). https://doi.org/10.1007/978-3-642-83189-8O’Callahan, R., Jones, C., Froyd, N., Huey, K., Noll, A., Partush, N.: Engineering record and replay for deployability: Extended technical report (2017). CoRR abs/1705.05937, http://arxiv.org/abs/1705.05937Ströder, T., Emmes, F., Schneider-Kamp, P., Giesl, J., Fuhs, C.: A linear operational semantics for termination and complexity analysis of ISO prolog. In: Vidal, G. (ed.) LOPSTR 2011. LNCS, vol. 7225, pp. 237–252. Springer, Heidelberg (2012). https://doi.org/10.1007/978-3-642-32211-2_16Undo Software: Increasing software development productivity with reversible debugging (2014). https://undo.io/media/uploads/files/Undo_ReversibleDebugging_Whitepaper.pd

A Case Study for Reversible Computing: Reversible Debugging of Concurrent Programs

International audienceReversible computing allows one to run programs not only in the usual forward direction, but also backward. A main application area for reversible computing is debugging, where one can use reversibility to go backward from a visible misbehaviour towards the bug causing it. While reversible debugging of sequential systems is well understood, reversible debugging of concurrent and distributed systems is less settled. We present here two approaches for debugging concurrent programs, one based on backtracking, which undoes actions in reverse order of execution, and one based on causal consistency, which allows one to undo any action provided that its consequences, if any, are undone beforehand. The first approach tackles an imperative language with shared memory, while the second one considers a core of the functional message-passing language Erlang. Both the approaches are based on solid formal foundations

On the relative expressiveness of higher-order session processes

By integrating constructs from the λ-calculus and the π-calculus, in higher-order process calculi exchanged values may contain processes. This paper studies the relative expressiveness of HOπ, the higher-order π-calculus in which communications are governed by session types. Our main discovery is that HO, a subcalculus of HOπ which lacks name-passing and recursion, can serve as a new core calculus for session-typed higher-order concurrency. By exploring a new bisimulation for HO, we show that HO can encode HOπ fully abstractly (up to typed contextual equivalence) more precisely and efficiently than the first-order session π-calculus (π). Overall, under session types, HOπ, HO, and π are equally expressive; however, HOπ and HO are more tightly related than HOπ and π