The objective of this course is to introduce the theory of formal languages, the related tools for the definition of their syntax (through grammars and automata), and the formalization of their semantics. In the settin of such formal tools, we illustrate techniques for modeling complex software systems and verifying their properties by means of methodologies based on automata and logics. 

01. Introduction to formal methods:
      01.01 The need for formal methods in software development.
      01.02 Formal languages and automata.
      01.03 Sentential form grammars.
      01.04 Chomsky classification.

02. Regular languages and finite-state automata:
      02.01 Deterministic finite-state automata.
      02.02 Nondeterministic finite-state automata.
      02.03 Nondeterministic finite-state automata with epsilon-transitions.
      02.04 Minimization and equivalence for finite-state automata.
      02.05 Finite-state automata and right-linear grammars.
      02.06 Closure properties of regular languages and pumping lemma.
      02.07 Regular expressions.
      02.08 Regular expressions and finite-state automata.

03. Context-free languages and pushdown automata:
      03.01 Free grammars and syntax trees.
      03.02 Chomsky normal form.
      03.03 Properties of context-free languages.
      03.04 Pushdown automata and relation with free grammars.
      03.05 Top-down parsing.
      03.06 LL(1) grammars.
      03.07 Parsing bottom-up.
      03.08 SLR, LR(1), and LALR(1) grammars.

04. Denotational semantics:
      04.01 Denotational semantics for non-cyclic sequential programs.
      04.02 Denotational semantics for the WHILE operator.
      04.03 Denotational semantics with blocks and procedures.

05. Operational semantics:
      05.01 Natural semantics for sequential programs.
      05.02 Natural semantics with blocks and procedures.
      05.03 Structural operational semantics.

06. Temporal logics and model checking:
      06.01 Kripke structures.
      06.02 Linear Temporal Logic.
      06.03 Computation Tree Logic.
      06.04 Model checking algorithms.

07. Laboratory activity:
      07.01 Specification of systems through Kripke structures.
      07.02 Model checking of systems specified through Kripke structures.
      07.03 Real-world case studies.
 

Although there are no mandatory prerequisites for this exam, students are strongly recommended to take it after Object-Oriented Programming and Modeling, Software Architecture and Engineering, Operating Systems, by respecting the prerequisites of these courses.

Knowledge and understanding: the student will be able to understand the syntax structure, the compiler rules, and the semantics of the most used programming languages, as well as the methodological principles behind the formal methods for design and verification of software systems that are illustrated in the program.

Applying knowledge and understanding: the student will be able to design the base modules of the compilers for programming languages and to specify and verify formally software systems through the tools used in the classrooms.

Making judgements: the student will be able to evaluate the correctness of syntax and semantics of any programming language and to represent and compare formally the several specifications of a software system under design and development.

Communication skills: the student will be able to illustrate in a proper way the semantic features of the programming languages and to describe formally the functionalities and the properties of a software system by using the modeling and verification tools used in the classrooms.

Learning skills: the student will learn how to describe formally syntax and semantics of programming languages and how to model and check software systems.

The teaching material prepared by the lecturer in addition to recommended textbooks (such as for instance slides, lecture notes, exercises, bibliography) and communications from the lecturer specific to the course can be found inside the Moodle platform › blended.uniurb.it

Teaching

Theory lectures and laboratory exercises, both face-to-face and on-line.

Attendance

Although recommended, course attendance is not mandatory.

Course books

Hopcroft, Motwani, Ullman, "Automi, Linguaggi e Calcolabilità", Addison-Wesley, 2009 or Aiello, Pirri, "Strutture, logica, linguaggi", Pearson, 2005 to cover the sections 01-03 of the program. The original version of the former book is Hopcroft, Motwani, Ullman, "Introduction to Automata Theory, Languages, and Computation", Addison-Wesley, 2007.

Sections 04 and 05 are inspired by Nielson, Nielson, "Semantics with Applications: An Appetizer", Springer, 2007.
 
Section 06 is covered by Clarke, Grumberg, Peled, "Model Checking", MIT Press, 1999.

Section 07 is based on the software tool NuSMV http://nusmv.fbk.eu/

Assessment

Individual project, written exam, and oral exam.

The individual project consists of modeling and verifying a software system with NuSMV. The project specification, one per session and the same for everybody, is published online at least one month before the beginning of every session, with delivery deadline by the noon of two days before the date of the written exam of interest. The project, even if passed, is valid only within the related session. The project text is given by the specification of a real system to model and verify. The student can freely choose the abstraction level of the system, the variants and configurations under analysis, and the properties to verify. Delivery is by email with subject LPVS: consegna progetto name_surname and must include source files with specifications and analysis results, each part adequately commented. The project mark is at most 10/30. The aim of the project is to check the capability of the student in the practical and autonomous use of the acquired skills about the modeling and verification of software.

The written exam can be given only after the delivery of the project related to the same session. Its duration is 90 minutes and it consists of practical exercises. Notes and didactical material can be used. The written exam mark is at most 20/30. The aim of the written exam is to verify the understanding skills about the theoretical topics of the program.

The oral exam is mandatory about the individual project and is optional about the course program. The optional oral exam yields a positive or negative adjustment (at most 5 points) to the final mark. The objective of the oral exam is to estimate making judgements as well as communication and learning skills.

For texts of projects and written exams, see this link.

Disabilità e DSA

Le studentesse e gli studenti che hanno registrato la certificazione di disabilità o la certificazione di DSA presso l'Ufficio Inclusione e diritto allo studio, possono chiedere di utilizzare le mappe concettuali (per parole chiave) durante la prova di esame.

A tal fine, è necessario inviare le mappe, due settimane prima dell’appello di esame, alla o al docente del corso, che ne verificherà la coerenza con le indicazioni delle linee guida di ateneo e potrà chiederne la modifica.