Philosophical aspects of proof theory

The purpose of this study is to establish levels from an inductive proof to an algebraic demonstration in lower secondary school mathematics. I propose that we can establish six levels of proof in lower secondary school mathematics as steps from an inductive proof to an algebraic demonstration on the basis of three axes (contents of proof, representation of proof, and students' thinking). To reach this conclusion, I firstly examine the meaning of ‘demonstration in lower secondary school mathematics’ and ‘proof in lower secondary school mathematics’, and show the relationships between them. Secondly, I set out four basic levels of proof, as seen from two aspects (contents and representation of proof). Thirdly, I subdivide them into six levels from the third aspect of students' thinking. Finally, I illustrate my discussion with a 7th grader's activities.

This paper investigates mathematics trainee teachers’ conceptions of proof writing in algebra at Copperbelt College of Education in Zambia. The ability to construct proofs seems to be an important skill for all mathematicians and those who have interest in mathematics education. However, literature shows that proof is widely acknowledged to be one of the most difficult aspects in the mathematics curriculum. The sample comprised of 35 male and 15 female third year mathematics trainee teachers. Data was collected by means of a self-administered questionnaire, a written diagnostic test and oral interviews. The three instruments were used to provide multiple views to triangulate the data. The results show that students seem to understand proof as a verification and confirmation tool. Many of them applied empirical approaches in their written proofs. They did not have sufficient knowledge of the right set of accepted statements such as axioms and could not identify which statements required proofs in mathematics. These findings suggest that students’ conceptions of proof were underdeveloped hence affecting their ability to produce valid proofs. These findings will assist in guiding curricula designers and teachers of proof related knowledge. DOI: 10.5901/mjss.2014.v5n14p331

A proof is a successful demonstration that a conclusion necessarily follows by logical reasoning from axioms which are considered evident for the given context and agreed upon by the community. It is this concept that sets mathematics apart from other disciplines and distinguishes it as the prototype of a deductive science. Proofs thus are utterly relevant for research, teaching and communication in mathematics and of particular interest for the philosophy of mathematics. In computer science, moreover, proofs have proved to be a rich source for already certified algorithms. This book provides the reader with a collection of articles covering relevant current research topics circled around the concept 'proof'. It tries to give due consideration to the depth and breadth of the subject by discussing its philosophical and methodological aspects, addressing foundational issues induced by Hilbert's Programme and the benefits of the arising formal notions of proof, without neglecting reasoning in natural language proofs and applications in computer science such as program extraction.

Computability is one of the fundamental notions of mathematics and computer science, trying to capture the effective content of mathematics and its applications. Computability Theory explores the frontiers and limits of effectiveness and algorithmic methods. It has its origins in Godel's Incompleteness Theorems and the formalization of computability by Turing and others, which later led to the emergence of computer science as we know it today. Computability Theory is strongly connected to other areas of mathematics and theoretical computer science. The core of this theory is the analysis of relative computability and the induced degrees of unsolvability; its applications are mainly to Kolmogorov complexity and randomness as well as mathematical logic, analysis and algebra. Current research in computability theory stresses these applications and focuses on algorithmic randomness, computable analysis, computable model theory, and reverse mathematics (proof theory). Recent advances in these research directions have revealed some deep interactions not only among these areas but also with the core parts of computability theory. The goal of this Dagstuhl Seminar is to bring together researchers from all parts of computability theory and related areas in order to discuss advances in the individual areas and the interactions among those.

We present results from a classroom-based intervention designed to help a class of grade 10 students (14–15 years old) learn proof while studying trigonometry in a dynamic geometry software environment. We analysed some students’ solutions to conjecture-and-proof problems that let them gain experience in stating conjectures and developing proofs. Grounded on a conception of proof that includes both empirical and deductive mathematical argumentations, we show the trajectories of some students progressing from developing basic empirical proofs towards developing deductive proofs and understanding the role of conjectures and proofs in mathematics. Our analysis of students’ solutions is based on networking Boero et al.’s construct of cognitive unity of theorems, Pedemonte’s structural and referential analysis of conjectures and proofs, and Balacheff and Margolinas’ cK¢ model, while using Toulmin schemes to represent students’ productions. This combination has allowed us to identify several emerging types of cognitive unity/rupture, corresponding to different ways of solving conjecture-and-proof problems. We also show that some types of cognitive unity/rupture seem to induce students to produce deductive proofs, whereas other types seem to induce them to produce empirical proofs.

There are various logic-based approaches to modelling concurrent programming. The use of logic for system development concerns both the specification step and the study of the operational aspects (through proof analysis and construction) of such development. This means that we have to consider different logical systems for different uses of logic. Moreover, we can also consider concurrency from both points of view: we want to reason and to specify systems where some concurrency aspects are involved, but also to have some operational interpretation of concurrency within logic (focusing on the concept of proof). For this purpose, it seems clear that we have to identify and to study, on the one hand, the role and the treatment of objects (representation, inheritance, modularity, communication, and so on) in this context, and, on the other hand, the interaction of work on proofs and concurrency with the Object-Oriented Programming paradigm.The ECOOP’96 workshop on ‘Proof Theory of Concurrent Object-Oriented Programming’ took place in Linz, Austria, in July 1996. Its objective was to provide an integrated forum for the presentation of research and the exchange of ideas and experiences in the topics concerned with proofs, concurrency and object-oriented programming (specification, proof development, and so on). The call for papers for this Special Issue of Mathematical Structures in Computer Science can be considered to have been a natural scientific continuation of the workshop.The papers selected for this Special Issue address some of the topics discussed in the workshop. They present different alternative frameworks that are effectively based on a proof-theoretic approach. They illustrate, from different points of view, the interest, potentialities and difficulties of dealing with such an approach in the design of object-based concurrent systems.

Mathematical argumentation is generally thought to be the paradigm of cogent reasoning. The concept of mathematical proof thus seems to be associated with necessity and enforcement, but not with freedom; however, in various ways a reference to freedom is also needed to understand the phenomenon of mathematical proof, for example, to distinguish it from a merely mechanical functioning. Moreover, without reference to these freedom-related aspects the value of incorporating proofs into the teaching of mathematics lacks an essential aspect of justification. The paper sheds light on some of these aspects and offers a picture of mathematical proof in tension between freedom and enforcement.

Mathematical Proof and Genre Theory

The explicative aim of this research is to investigate the optics of proof format preferences held by prospective mathematics teachers (PMTs), in an effort to assess the effect that such preferences may have on their understanding of geometric proofs. The researchers employed a qualitative case study approach, in which six PMTs participated in Focus Group Discussions (FGDs) on the three styles of proof: paragraph proof, two-column proof and flow-chart proof. The methodology employed also focused on the formatting models by exploring the participants’ suggestions regarding each format in order to determine their cognitive responses as well as their preferences. The study exposes different preferences among PMTs which are a result of their personal cognitive style and experience with proofs. Some of the PMTs preferred the two-column format due to its systematic and logical nature, other PMTs preferred the storytelling nature of the paragraph proof format sponsored also flow-chart representation. These preferences bring out the requirement for the development of pedagogical strategies that employ different proof formats in order to meet the needs of different types of learners for effective understanding. In summary, this research demonstrates the need for customizing proof instruction to different students’ needs which can hopefully enhance PMTs’ responses and interactions with the concept of mathematical proofs. The practical outcomes show that teachers should not be afraid to think in more flexible witnessing forms of proof in order to aid students learning while minimizing the cognitive load in line with the principles of constructivist learning. It would be worthwhile however to extend this research and examine what these preferences would mean for the future and how those would fit within the context of online education with the overall aim of creating a better mathematics curriculum that is more effective and has a wider reach.

Intuitionism and the liar paradox

PROOF CHECKING THE RSA PUBLIC KEY ENCRYPTION ALGORITHM

An account of mathematical understanding should account for the differences between theorems whose proofs are “easy” to discover, and those whose proofs are difficult to discover. Though Hilbert seems to have created proof theory with the idea that it would address this kind of “discovermental complexity”, much more attention has been paid to the lengths of proofs, a measure of the difficulty of verifying of a given formal object that it is a proof of a given formula in a given formal system. In this paper we will shift attention back to discovermental complexity, by addressing a “topological” measure of proof complexity recently highlighted by Alessandra Carbone (2009). Though we will contend that Carbone’s measure fails as a measure of discovermental complexity, it forefronts numerous important formal and epistemological issues that we will discuss, including the structure of proofs and the question of whether impure proofs are systematically simpler than pure proofs.