type systems
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2022 ◽  
Vol 6 (POPL) ◽  
pp. 1-28
Author(s):  
Matthias Eichholz ◽  
Eric Hayden Campbell ◽  
Matthias Krebs ◽  
Nate Foster ◽  
Mira Mezini

Programming languages like P4 enable specifying the behavior of network data planes in software. However, with increasingly powerful and complex applications running in the network, the risk of faults also increases. Hence, there is growing recognition of the need for methods and tools to statically verify the correctness of P4 code, especially as the language lacks basic safety guarantees. Type systems are a lightweight and compositional way to establish program properties, but there is a significant gap between the kinds of properties that can be proved using simple type systems (e.g., SafeP4) and those that can be obtained using full-blown verification tools (e.g., p4v). In this paper, we close this gap by developing Π4, a dependently-typed version of P4 based on decidable refinements. We motivate the design of Π4, prove the soundness of its type system, develop an SMT-based implementation, and present case studies that illustrate its applicability to a variety of data plane programs.


2022 ◽  
Vol 6 (POPL) ◽  
pp. 1-31
Author(s):  
Giuseppe Castagna ◽  
Mickaël Laurent ◽  
Kim Nguyễn ◽  
Matthew Lutze

We extend classic union and intersection type systems with a type-case construction and show that the combination of the union elimination rule of the former and the typing rules for type-cases of our extension encompasses occurrence typing . To apply this system in practice, we define a canonical form for the expressions of our extension, called MSC-form. We show that an expression of the extension is typable if and only if its MSC-form is, and reduce the problem of typing the latter to the one of reconstructing annotations for that term. We provide a sound algorithm that performs this reconstruction and a proof-of-concept implementation.


2022 ◽  
Author(s):  
Munusamy Krishnamurthy ◽  
Philip Hope ◽  
P Ramar ◽  
A. A. Boopathi ◽  
Srinivasan Sampath ◽  
...  

Photo-catalysts offer a simple catalytic method with widespread applications like degradation of polluting dyes, hydrogen generation from water, etc., in the presence of a photon source like sunlight. The development of a second-generation photo-catalyst in the form of a nanocomposite is an integral part of research to improve the practical usefulness and efficiency of the process. A systematic study using the active material with controlled functional groups is required to understand the process in detail as well as to develop efficient photocatalytic systems. In this paper, we report the design, synthesis, detailed physicochemical studies, and self-assembly of interesting materials where fullerenes have been functionalized with polycyclic, aromatic, conjugated, butterfly-shaped molecules like Tetrabenzofluorene (TBF) using a well-known click chemistry approach. Detailed analyses using spectroscopic, electrochemical, and microscopic or X-ray diffraction (single crystal) techniques were undertaken for a clear understanding of their photophysical or self-assembly behavior. The functionalized fullerene material was mainly used so that comparative results could be presented where two units (mono adduct) or twelve units (hexakis adduct) of TBF molecules were attached separately. These comparative studies were beneficial for unambiguous interpretation of results and drawing definitive conclusions regarding the energy transfer with cascade-type systems. Finally, those results were useful for the logical understanding of photo-catalytic experiments using those designer fullerene materials.


2022 ◽  
pp. 331-345
Author(s):  
Conor McBride ◽  
Fredrik Nordvall-Forsberg
Keyword(s):  

2022 ◽  
pp. 368-379
Author(s):  
Kimmi Kumari ◽  
M. Mrunalini

The highly interconnected network of heterogeneous devices which enables all kinds of communications to take place in an efficient manner is referred to as “IOT.” In the current situation, the data are increasing day by day in size as well as in terms of complexities. These are the big data which are in huge demand in the industrial sectors. Various IT sectors are adopting big data present on IOT for the growth of their companies and fulfilling their requirements. But organizations are facing a lot of security issues and challenges while protecting their confidential data. IOT type systems require security while communications which is required currently by configuration levels of security algorithms, but these algorithms give more priority to functionalities of the applications over security. Smart grids have become one of the major subjects of discussions when the demands for IOT devices increases. The requirements arise related to the generation and transmission of electricity, consumption of electricity being monitored, etc. The system which is responsible to collect heterogeneous data are a complicated structure and some of its major subsystems which they require for smooth communications include log servers, smart meters, appliances which are intelligent, different sensors chosen based on their requirements, actuators with proper and efficient infrastructure. Security measures like collection, storage, manipulations and a massive amount of data retention are required as the system is highly diverse in its architecture and even the heterogeneous IOT devices are interacting with each other. In this article, security challenges and concerns of IOT big data associated with smart grid are discussed along with the new security enhancements for identification and authentications of things in IOT big data environments.


Author(s):  
Nuo Li ◽  
XiaoHua Deng ◽  
JunMing Yao ◽  
ZhiYong Ni ◽  
Franco Pirajno ◽  
...  
Keyword(s):  

2021 ◽  
Vol 41 (1) ◽  
Author(s):  
D. S. Almeida Júnior ◽  
M. M. Freitas ◽  
A. J. A. Ramos ◽  
A. Soufyane ◽  
M. L. Cardoso ◽  
...  
Keyword(s):  

2021 ◽  
Author(s):  
◽  
Julian Mackay

<p>A significant issue in modern programming languages is unsafe aliasing. Modern type systems have attempted to address this in two prominent ways; immutability and ownership, and often a combination of the two [4][17]. The goal of this thesis is to formalise Immutability and Ownership using the Coq Proof Assistant, a formal proof management system [13]. We encode three type systems using Coq; Featherweight Immutable Java, Featherweight Generic Java and Featherweight Ownership Generic Java, and prove them sound. We describe the challenges presented in encoding immutability, ownership and type systems in general in Coq.</p>


2021 ◽  
Author(s):  
◽  
Julian Mackay

<p>A significant issue in modern programming languages is unsafe aliasing. Modern type systems have attempted to address this in two prominent ways; immutability and ownership, and often a combination of the two [4][17]. The goal of this thesis is to formalise Immutability and Ownership using the Coq Proof Assistant, a formal proof management system [13]. We encode three type systems using Coq; Featherweight Immutable Java, Featherweight Generic Java and Featherweight Ownership Generic Java, and prove them sound. We describe the challenges presented in encoding immutability, ownership and type systems in general in Coq.</p>


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