Lolisa: Formal Syntax and Semantics for a Subset of the Solidity Programming Language in Mathematical Tool Coq

The security of blockchain smart contracts is one of the most emerging issues of the greatest interest for researchers. This article presents an intermediate specification language for the formal verification of Ethereum-based smart contract in Coq, denoted as Lolisa. The formal syntax and semantics of Lolisa contain a large subset of the Solidity programming language developed for the Ethereum blockchain platform. To enhance type safety, the formal syntax of Lolisa adopts a stronger static type system than Solidity. In addition, Lolisa includes a large subset of Solidity syntax components as well as general-purpose programming language features. Therefore, Solidity programs can be directly translated into Lolisa with line-by-line correspondence. Lolisa is inherently generalizable and can be extended to express other programming languages. Finally, the syntax and semantics of Lolisa have been encapsulated as an interpreter in mathematical tool Coq. Hence, smart contracts written in Lolisa can be symbolically executed and verified in Coq.

ON-LINE CORRESPONDENCE AS SELF-TEACHING

The paper presents further interpretation of the first results related to implementation of the linguodidactic project regarding teaching Russian as a Foreign Language based on the students’ educational and speech activity, which is carried out in the course of on-line correspondence with native speakers. The first part of the paper state the initial principles of organization and implementation of the project defined by N. D. Golev: the theoretical and methodological basis, areas of linguo-methodical activity, technology of on-line correspondence. The second part is devoted to description of this project implementation experience in respect of students’ self-teaching, which is at first stage focused on the study and acquisition of the new different level of the language and communicative-speech units taken first of all from Internet sources as well as from Russian correspondents’ letters and entered into actual contexts of a produced letter. The second stage deals with the review of the created text in the form of error correction carried out either on one’s own or together with a teacher. Upon completion of work the students present the revised text of the letter which is subject to evaluation.

Traduções em prosa da Odisseia de Homero: exemplos e problemas

My aim is to discuss four Portuguese translations of Homer’s Odyssey. Two were written in prose (by Dias Palmeira/ Alves Correia and by Jaime Bruna), in the 20th century, and two in free verse (by Frederico Lourenço and by Donaldo Schüler), in the 21st century. A quick review of these examples reveals that all of them want to recover Homer’s narrative fluidity, without giving attention to its main formal aspects – which surely enhance the understanding of the contents. As to the latest versions, it is possible to claim that, despite the impressive differences between them, deployment of a free verse betrays the goal of only establishing a line by line correspondence between the original text and the translation, and in the end the principles of a prose translation seem again to guide these versions to Portuguese.