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We invite you to attend the defense of the doctoral thesis of Ing. David Kozák from the Department of Intelligent Systems, FIT BUT, which will take place on Wednesday, December 10, 2025, at 10:30 a.m. in meeting room G108 at FIT VUT. The supervisor of the dissertation entitled "New methods of static analysis not only for ahead-of-time compilers of object-oriented languages" is Prof. Tomáš Vojnar.

David Kozák's dissertation deals with the use of static analysis methods in the context of ahead-of-time compilation of object-oriented languages such as Java. Kozák focuses on the possibilities of applying these techniques in automated analysis and, at the same time, in the field of software architecture reconstruction in a microservices environment. David's research work has a specific application level. The tool in which he implemented most of his research is called GraalVM Native Image. It performs ahead-of-time compilation and has been under development for a long time at the Oracle Labs research institute. Kozák is part of the GraalVM team there.

The main goal of the author's work was to streamline the chain of processes connecting points-to static analysis and the subsequent work of the ahead-of-time compiler. Static analysis can be broadly defined as anything that analyzes a program without running it, with the aim of determining the properties of the program or verifying that it works correctly according to a specified definition of correctness. From the outset, this method has been closely linked to compilers. Static analysis applied to the compiler environment must be fast, efficient, and computationally inexpensive. The specific goal of the author's research was to maintain the reliability and accuracy of points-to static analysis, but at the same time to speed it up, i.e., to approximate the strength of another type of static analysis: rapid type. In addition, this had to be achieved in an ahead-of-time compiler environment, in this case working with a low-level representation of the Java programming language called bytecode. As the name suggests, ahead-of-time compilation into machine code takes place before the program is run as a separate process, only once and without the "luxury" of being able to subsequently interpret code that has not been compiled or, if necessary, recompile certain methods at runtime. Therefore, everything that could be executed is compiled, which is computationally demanding by its very nature, and the resulting binary file is usually large. This is where the motivation lies to streamline and speed up static analysis while maintaining its correctness.

The Native Image compiler that Kozák works with uses type points-to analysis working with object types (classes). Kozák used the saturation technique, which can be simplified as a compromise between points-to analysis and rapid-type analysis. Its main idea can be described as follows: We look at which specific implementations of a given type have been created (instantiated) and use only those. We cover the parts of the program that we can analyze accurately with points-to analysis methods. Conversely, if we have too much data available for some parts of the program, we use rapid-type analysis for them. The result is accuracy close to the outputs of points-to analysis and speed very close to that offered by rapid-type analysis.

Another part of Kozák's dissertation and research task was the design of an extension to the Native Image tool's points-to analysis called SkipFlow. This extension now tracks not only objects but also the flow of primitive values, while using predicate edges to prevent the propagation of values from unreachable branches (dead code) of the program. SkipFlow reduced the load on the compiler and offered more accurate analysis at the cost of a slight increase in runtime and with the benefit of subsequent faster work by the compiler itself.

Kozák's research also has a second, perhaps somewhat surprising and atypical field of application for static analysis – the sphere of microservices, or rather understanding the impact of their interdependencies. And this is more the domain of software engineering. Today, applications are developed in the form of a series of smaller microservices. The problem, however, is that it is difficult to track the communication between individual parts and the impact of changes in individual microservices on other services. Kozák again used the Native Image tool, this time to obtain information about each individual service, and then used this to create a holistic view of the entire application. The compiled version of the application can thus be used to reconstruct the high-level architecture and its completely up-to-date visualization, which can be passed on to the software architect. Kozák also participated in the creation of the SAVAT tool, which is capable of analyzing the impact of changes within the time series of individual microservice versions. Bottom line: David Kozák's dissertation is a step towards unifying three previously largely separate areas: compilers, interprocedural static analysis covering the entire program, and software engineering.

When asked about the key results of his research, David Kozák is clear: "I am most proud of SkipFlow, an extension of points-to analysis that tracks primitive values and monitors dependencies between program branches. Why? Because we have achieved the ideal result here: we have created an analysis that is both more accurate and faster. Then I would mention saturation, because by combining two types of analysis and calculating very accurately only where it makes sense, we were able to achieve almost identical results to a more accurate analysis, but in significantly less time." However, when taking stock, David also mentions more general points: "I am satisfied that this is not purely basic research, but that everything is integrated into a real tool, Native Image, and that saturation and SkipFlow are automatically enabled in this tool. This means that anyone who uses Native Image also uses the results of my dissertation. I like to focus my research on what is used in practice. I enjoy contact with industry and the real-world application of technology." David would like to thank his colleagues from the VeriFIT research group for their consultation and support during his research. As for his future work plans, he states that he would like to continue to straddle academic research and industry. His dream goal is to assemble a larger team of people who would participate in research within the GraalVM team, including bachelor's and master's students interested in compilers.

We would like to add that another public defense of a doctoral thesis is planned at our faculty in the same week. The author of the dissertation "Late Binding of Variables in AgentSpeak(L) Interpreters" is Ing. František Vídeňský from the Department of Intelligent Systems, and his supervisor is doc. František Zbořil. The public defense of this dissertation will take place on Friday, December 12, 2025, at 1:00 p.m. in room G108.

We wish both researchers continued success and joy in their field.

Ing. Jaroslav Kadlec, Ph.D., a graduate of FIT VUT with a focus on computer graphics (Department of Computer Graphics and Multimedia), completed his doctoral studies in 2010. Since 2014, he has been employed by Thermo Fisher Scientific, currently in the position of software manager.

What led you to choose to study information technology at university? Were you already passionate about computers and electronics in high school? Or was it more of a pragmatic choice driven by the prospect of a well-paid job?

As a child, I was fascinated by all things electronic. If my parents left me alone, I would end up dismantling and taking apart some of the electronics in our home, even though I didn't really understand how they worked. Electronics and electricity were my obsession. I attended a sports-oriented elementary school and did track and field. One of my classmates introduced me to his brother, who was studying electrical engineering at a technical high school with a focus on microprocessor technology. The two of them had an Atari computer, and I was completely fascinated by what they could do with it. Logically, I wanted to go to the same school. And from my first year of high school, I was determined to learn how to program. It was such a huge challenge compared to everything else I had experienced in my life so far that I really turned into the proverbial nerd. I started programming with Basic, then moved on to Pascal, Assembler, and finally C and C++, the latter two at college. So yes, from sixth or seventh grade on, my path was pretty clear.

It really seems like you had your path figured out. In that case, was your first year of college a challenge for you, or did you get through it without any major problems thanks to your long-term interest in programming and electronics? How do you remember your bachelor's studies?

I was actually part of the first generation of people who enrolled at FIT (the faculty was established in 2002, editor's note). In my freshman year, I started as a student at the Faculty of Electrical Engineering and Computer Science (FEI) at BUT, which offered a degree program in Computer Science and Information Technology. During my first year, the faculty was divided into FIT and FEKT (Faculty of Electrical Engineering and Communication Technologies), and thanks to my grades, I had the opportunity to choose. I knew exactly that I wanted to continue at FIT. I became increasingly interested in computer graphics and multimedia, and in fact all the fields that were developing there at the time under Pavel Zemčík.

What attracted you so much to graphics and imaging methods that they became your specialization during your studies at FIT?

I was interested in computer games and their programming. I had already put together a few smaller games in Pascal. When I got to college, I wanted to improve my skills. At that time, there were already graphics cards with OpenGL, which could be used to create lights and other things that I couldn't calculate in Pascal before. This led me to questions about how such enormous computer performance actually works at the processor level and so on. And again, it was a huge challenge. Graphics accompanied me throughout my studies. The topic of my thesis was user interface architectures in a 3D environment, and the output of my thesis was movement in a virtual environment, navigation in it, etc. At the end of my master's studies, I was faced with a choice: either accept the offer to continue with a doctorate, or join the army, because I had already been drafted. So I admit that my motivation to pursue a doctorate was twofold...

Were you attracted to a doctorate purely from a professional standpoint?

There were several motivations: I like to explain things, so I wanted to teach. At the same time, I wanted to learn something new myself, to move forward. And in my case, "forward" meant moving in the direction of automatic user interface generation. In the end, my PhD took seven years. In the meantime, we had a child, so it was challenging. And yes, because of the difficulty, I even got to the point where I was thinking about giving up my PhD due to the exhausting time demands.

During your PhD, you got to work in a rather unusual field of industry: you were involved in interactive simulations for training armed forces. How did you come by this opportunity?

I was lucky. I felt the need for a financial injection for our family with a small child. The offer then came through another doctoral student at the faculty who was already working for VR Group. I found it interesting and thought to myself, "Simulators are graphics, and that's what I want to do." I started part-time and after two years went full-time. In the end, I worked mainly on modeling—from ballistics to combat vehicle control to simulations of the behavior of large groups of people and the surrounding environment. We also collaborated with the Integrated Rescue System, to which we supplied simulations of floods and fires, for example. I also enjoyed connecting software with hardware. I generally consider the connection between industry and academia to be a good thing. That's why we at Thermo Fisher try to stay in touch with FIT, collaborate with the faculty, offer interesting topics to its students, etc.

You are now in your eleventh year at Thermo Fisher Scientific. What attracted you to working for such a large company?

I was looking for a company that would once again offer me a combination of things that made sense to me. What I liked about Thermo Fisher was that the microscopes they manufacture serve a good purpose—for the production of medicines, the study of viruses, materials science, chip manufacturing... And humanity, good leadership, and good relationships between people at work are extremely important to me. At the time, I had information that this was how things were set up at Thermo Fisher. Looking back, I've always been lucky to have good people around me. For me, that's a huge asset in any job.

What has your career path been like at Thermo Fisher? What does a typical project you are working on today look like?

I joined as a senior software developer. It was a really sharp start, right off the bat, three days after I started, I flew to the United States to bring back the know-how of a company we had acquired at the time. As a developer, I have a very strong need for things to work and for the people who will use our results to be satisfied with them. And after the transfer of development here to Brno, I felt compelled to make sure that everything worked. Not just the development and code itself, but also that the software was getting into production and to users correctly, for example. I smoothly transitioned to setting up processes, communicating with production, collecting requirements, etc. I started doing things that developers don't normally do. After two years, the company came to me with an offer for a management position. At first, I led a small team, and hand in hand with that, I learned to perceive my activity and communication differently, how my actions affect others. I began to develop outside the technical part of development. The team grew, I moved on to other groups, I led an international team, and finally, two and a half years ago, I moved from materials science to a team that works for the semiconductor industry and now has about 80 members. And that's a different world and another huge challenge. I no longer deal with the technical side of things, I don't program. It has become just a hobby, but there is no room for it at work.

Today, you lead teams of developers and are also involved in deciding who will expand them. What strengths do you look for in job applicants?

I have found it best to choose people with the right attitude, who are enthusiastic about their work, because such inquisitive applicants learn better. In interviews, I don't primarily look for hard skills, such as the ability to program in a specific language. It's important that they are able to communicate well, know how to collaborate, and don't mind doing so. Because nowadays, everything is so complex that no one can do anything alone. I look for people who can work in a team. And also, for example, aren't afraid to work with hardware.

Looking back on your studies and career, how do you see FIT contributing to your professional path? What challenges did you face while studying at this faculty, and what obstacles did you have to overcome?

In my case, it was very time-consuming. Because I need to do things in such a way that I am convinced they are good enough to be submitted, I spent much more time on them than was necessary. From high school to the end of college, I didn't really have much of a social life. It was a heavy burden that I struggled with later in my career as well. On the other hand, FIT gives you a huge number of opportunities, offers lots of new topics, and opens many doors. You walk through some of them, and just peek through others. The school gives you the conditions and inspiration to learn. And FIT does that very well.

I took advantage of the open door to graphic design. And I also took advantage of the help of many great people. Honza Černocký, Adam Herout, Pavel Zemčík, Víťa Beran... For me, FIT is also great from the perspective of my current job role: I feel that FIT graduates are very well prepared for teamwork, they are less theoretical and more practical. As I said, nowadays, you can't do anything on your own. And it's clear that FIT is moving in the right direction in terms of team projects.

The interview with Jaroslav Kadlec is the first in a series of interviews with our successful graduates, which we will be publishing in the coming weeks.