After a long and brave battle with a serious illness, our dear friend and colleague Slavik Jablan passed away on 26 February 2015. The world is deprived of a remarkable mathematician, a great artist, a wonderful man and a dear friend. He made significant contributions to many areas of mathematics: geometry, group theory, mathematical crystallography, the theory of symmetry, antisymmetry, colored symmetry, combinatorial geometry, knot theory, visual mathematics and mathematical art.

Slavik Jablan was born on 10 June 1952 in Sarajevo, Yugoslavia (now in Bosnia-Herzegovina). He grew up in Sarajevo, Dubrovnik and Belgrade. He studied at the University of Belgrade and graduated in 1977 in theoretical mathematics from the Faculty of Mathematics, University of Belgrade, where he also obtained his MA in 1981 and PhD in 1984, with a thesis entitled Theory of Simple and Multiple Antisymmetry in E² and E² ∖ { O } . In 1985 and 1988, he pursued an advanced scientific program in colored symmetry at the University of Kishinev in the former USSR (now Chişinău, Republic of Moldova). He also held numerous visiting positions, including in the USA and Canada (1990): the University of Wisconsin-Madison; Indiana University Bloomington, Department of Anthropology; Tsukuba University, Tsukuba, Science City, Japan (1999); Fulbright Scholar, USA (2003–2004); and many others.

Slavik Jablan started his career at the PTT School center and at the Pedagogical Academy for Teacher Training in Belgrade, where he worked until 1984. He moved to the Faculty of Philosophy, Department of Mathematics at the University of Niš in southern Serbia, where he was a professor of geometry. In 1999, he returned to Belgrade, to work at the College of Information and Communication Technology. He designed and taught a visual mathematics course for designers at the Metropolitan University in Belgrade. Over the years, he was a Research member of the Mathematical Institute of the Serbian Academy of Science and Arts, the Editor of the VisMath electronic journal (http://www.mi.sanu.ac.rs/vismath) and the Editor in Chief of Symmetry. He was a member of the Advisory Board of The International Society for the Interdisciplinary Study of Symmetry, as well as a member of many other math societies.

His scientific roots lie in deriving and cataloging groups of simple and multiple antisymmetry based on an antisymmetry characteristic (AC) method that he developed in his PhD thesis. Using AC methods, it was possible to derive and to distinguish different antisymmetry groups based on their antisymmetry characteristic. He was also interested in enantiomorphism forms and chirality. His first PhD student Ljiljana Radovic continued this work and implemented the method of antisymmetry characteristic in the computation of multiplied antisymmetry groups by computer. He published more than 30 scientific papers on this topic, as well as several monographs: Theory of Symmetry and Ornament, APXAIA, Belgrade, 1984 (in Serbo-Croatian); Geometry in Pre-Scientific Period & Ornament Today, Math. Inst., History of Math. and Mech. Sci., 3, Belgrade, 1989; Theory of Symmetry and Ornament, Math. Inst., Belgrade, 1995 (http://www.mi.sanu.ac.rs/jablans/mon.htm); Symmetry, Ornament and Modularity, World Scientific, New York, 2002.

Starting in the mid-1990s, Slavik Jablan expanded his interests to knot theory, an area of low-dimensional topology. His unique background enabled Slavik to discover various patterns in the world of knots and their invariants. In 1995, he proposed the so-called Bernhard–Jablan conjecture about an invariant called the unknotting number. His idea of utilizing Conway notation as well as knot and link families is the core of the knot theory software package LinKnot that he developed together with Radmila Sazdanovic. Together they  coauhored a book titled LinKnot: Knot Theory by Computer (World Scientific, Singapore, 2007) along with a webMathematica version of LinKnot (http://math.ict.edu.rs/). Slavik published many significant scientific papers with theoretical and experimental results, and influenced the area of knot theory through collaborations and inspiring students to take up this field of study. Till the very end, Slavik was working with his last PhD student, Ana Zekovic, who defended her PhD thesis “Conway notation and its appliance in knot distance determination methods, in knot theory” on the same day when Slavik Jablan passed away.

Slavik Jablan was one of the leading experts in visual mathematics. All his life, he was building bridges between science and art. He was interested in the history of ornamental art, patterns, modularity, visual perception, Celtic art, ornamental design, key-patterns, Roman mazes and labyrinths, Paleolithic ornaments and op art puzzles. His contribution to the symmetry approach of ornamental design by SpaceTiles, KnotTiles and especially OpTiles based on modularity will be remembered by all. Slavik was an accomplished painter and math artist with more than 15 solo exhibitions, and his work on Two-Colored Ornamental Tilings based on modularity and Mathematics and Design (1998) winning one of the awards at the International Competition of Industrial Design and New Technology CEVISAMA1987 (Valencia, Spain).

He was an avid promoter of the concept of visual geometry and visual mathematics, with emphasis on symmetry in visual and ornamental art, at numerous conferences, such as ISIS-Symmetry, BRIDGES, Gathering for Gardner, as well as in the series of lectures all around the world: at the University of Wisconsin (Madison, Department of Mathematics), Indiana University (Bloomington, Department of Anthropology), Technische Universität (Vienna, Austria, Department of Geometry), Symmetry and Visual Perception at Faculty of Philosophy (Belgrade, Department of Experimental Psychology), Symmetry and Visual Arts at the National Museum (Belgrade), Classification of Ornaments at the Museum of Contemporary Art (Belgrade). His love and passion for ornamental art lasted all his life. He was one of the founders of the Experience Workshop Math-Art Movement and creator of the course “Visual Mathematics and Design” at the Faculty of Information Technologies (Belgrade), and his ideas and contributions were essential for the success of the Tempus Project on Visual Mathematics. He was invited to give the contribution “Classification of Ornaments” for the catalog of the exhibition “Memory Update: Ornaments of Serbian Medieval Frescoes”, held at the Museum of Applied Arts, Belgrade, November 2013–March 2014. In November 2014, he had his last solo exhibition, “Do you like Paleolithic ornamental art?” in the Radio Television of Serbia Gallery in Belgrade.

Slavik Jablan was born 1952 in Sarajevo at a time midway between the two dramatic events by which Sarajevo is otherwise known to the outside world: the assassination of Archduke Ferdinand, which set off World War I, and the siege of Sarajevo, which marked the disintegration of modern Yugoslavia. Slavik emerged from this second event to become a prominent spokesman and practitioner for symmetry in its mathematical and artistic forms. In the early 1990s, he received a grant to travel to America to become acquainted with prominent figures, such as H.S.M. Coxeter (who had recently helped organize an Escher conference in Rome) and Arthur Loeb, whose book on color symmetry dealt with a topic much like Slavik’s own 1984 Belgrade thesis (published in English as Theory of Symmetry and Ornament, 1995).

Growing out of this trip, he received a Fulbright scholarship to return to America to work with me and others on real-world symmetry. However, this was suspended when the war in Yugoslavia intervened. For the next few years, he made many contacts in Europe, especially via the ISIS-Symmetry organization of Georgy Darvas and Denes Nagy. By 1998, he founded the electronic journal VisMath, where “visual mathematics” came to include not only traditional geometric topics, but decorative art (at which Slavik was an expert) and symmetries of primitive and ethnographic art (providing an outlet, for example, for the work of Paulus Gerdes, who sadly died a few months before Slavik). I was honored to have him accept a small paper of mine to be the first paper in the first issue, and as editor, he enlivened the paper, so that it lights up like a shopping mall. Slavik’s own art can be seen in several papers in the MathArt section of VisMath. The Bridges organization was founded in America about the same time, and Slavik became an early participant in its annual conferences, including editing one of the proceedings. At the Bridges conference that year, he entertained some of the participants by producing almost instant watercolors, including marine scenes from the Adriatic coast of his homeland. Each New Years, he produced modular or op art calendars. Not until 2004 was he able to get his 1992 Fulbright reinstated, and he used the time in Wisconsin to complete his knot theory book (published with Radmila Sazdanovic) and work with Jay Kappraff in New Jersey.

At the time of his death, Slavik was the editor not only of VisMath, but of the electronic journal Symmetry published in Switzerland. It will be hard to fill his niche in the world of mathematics and art, impossible to fill it in the memories of those who were his friends.

I had known Slavik since 1988, and we met in the following year. Twenty seven years is a long time: uncountable correspondence, several common projects, many personal meetings. Our relation was not restricted to collaboration in science. We visited each other, and when his home country was the subject of bombing by foreign armed forces, my wife and I invited him and his kind wife Jadranka to survive the hard period in our home in Budapest. Although they did not want to leave their apartment unattended in that period, they did not forget it, even until our last meeting last autumn. Of course, there were less and more intensive periods in the contact over such a long time, but we could recover our collaboration when our mutually beloved common theme, symmetry, demanded it. The last few years belonged again to collaborative periods, and we had further plans that, unfortunately, will never be realized. I appreciated greatly his scholarly intellect, his wide knowledge both in the sciences and the arts and his smart attitude.

I first met Slavik Jablan somewhere in the middle of the 1990s during a mathematics and design conference in San Sebastian, Spain, where his lecture was elected “best lecture of the meeting”. We would keep in touch, through many conferences and uncountable emails during the years. Slavik came to Belgium several times, and I always programmed him as the first speaker of my conferences on “Mathematics and Art”, to make sure to have a good start.

As a foremost member of many mathematics and art societies, he started the very first “Visual Mathematics” website, at times when making and spreading Internet sites was not as evident as it is now. It became a top virtual library on mathematics and art. I stand behind the point of view that it was Slavik who coined the term “visual mathematics”, though I know he found this statement exaggerated. In 2012, he gave me a copy of a chapter of an unusual course, titled “visual mathematics”, which he was teaching to graphical designers at the Belgrade Metropolitan University. I tried to teach that chapter to my own architecture students in Belgium and I can confirm firsthand that it would be a pity if this course were to not be published nor taught in the future. It was Slavik’s opinion that designers and artists have the obligation and right to know mathematics, and that was right.

Over the years, we discussed many times how to find some support for those visual mathematics activities. Several draft project versions were written, rejected for all kinds of reasons, sometimes related to the political situation of Serbia. However, Slavik persisted, and in the end, we got a Tempus project approved on visual mathematics. Symbolically, the project finished in 2014, as if he had waited for it to be completed. We will not forget how much he enjoyed the attention of the general public for mathematics, during the “Belgrade Summer School on Visual Mathematics”, in 2014, at the shores of the River Danube. Slavik was the foremost mathematician in the group, and that was right.

After a talk of mine in Israel somewhere in 1998 about the oldest mathematical object, the Congolese Ishango rod, we engaged in a discussion about this object. We did not entirely agree, but on the contrary, that was not a problem. Later, in 2007, he would even come to my conference “Ishango, 22000 and 50 years later: the cradle of mathematics?” at the Flemish Royal Academy of Belgium. Additionally, in 2013, a contribution by his hand, entitled “A Second Opinion on the Ishango Rod”, would be a part of a chapter in my book “Belgium + Mathematics”. This genuine interest he had for Africa was also confirmed in a kind of expedition we held in Buenos Aires, Argentina. Someone informed us that an Argentine citizen had a large collection of Congolese fabrics that he did not exactly know what to do with and how they should be grouped together, and for some reason, he did not want to follow the official steps. Yet, we went to visit him, took numerous pictures and crowned the expedition with a paper on a group theory classification of Congolese fabrics in Buenos Aires. Mathematics combined with adventure, and that was fun.

Because of that Tempus project, I finally had an official reason to visit Slavik in Belgrade, in April 2013. I thought it would be awkward, since, after all, his Serbia had been heavily bombed by NATO, in 1999. He reported about the bombing to me from his side, while I was e-mailing from Brussels, the city of NATO’s head quarters. Still, the welcome in Belgrade could not be better, and I have hardly ever been in a country as hospitable as Serbia. Additionally, even posthumously, he continues to spread the message about the mathematical beauty of Serbia, through the exhibition “Memory Update: Ornaments of Serbian Medieval Frescoes”. This exhibition, to which he contributed the mathematical aspects, is starting a tour around the world. His spirit will travel with it.

Slavik was a prince among mathematicians. I had a long and fruitful history with him and also with his wonderful wife Jadranka and son Ivan. In 2005, he got a Fulbright, and we spent three months together at NJIT with Slavik living in my town of South Orange. During this time, we wrote a couple of papers together and had many adventures. When it came time to part, he told me that he wanted to give me a gift. At the end of the weekend, he presented me with two large watercolor paintings. Being overwhelmed by my own work, I put them in my attic. It was three years later that I took a careful look at them. They were masterpieces, and they now adorn my apartment. One in particular is priceless. It keeps another of his still life paintings company in a place of honor in my living room. For this past year, we have been working on a book to help faculty who wish to teach a course in Math of Design for which we have contracted with World Scientific. Although he cannot complete this task, he has bequeathed it to two former students of his, Ljiljana Radovic and Radmila Sazdanovic. They will carry on this work, which will be a fitting tribute to Slavik. In 2008, I paid a visit to Slavik in Belgrade. Ivan, Slavik’s son, who is an archivist of Serbian history and culture, took me on a historical tour of Belgrade, while Jadranka shared her novel approach to musical theory with me. Ivan is a fine chorale singer in the Serbian choral tradition. It so happened that in 2012, my daughter-in-law was visiting Belgrade as a choral conductor during which Slavik showed her great hospitality. Slavik was broad gauged in his approach to art and life with strong interests in both music, art and design. He also had a passion for the history of design going back as far as 23,000 BC to the Mezin culture. He collected designs through all of Europe, but particularly in Eastern Europe. His essay on mathematics in the art of Salvador Dali, never published, is a masterpiece. In recent years, he became one of the world’s authorities on knot theory, establishing a fruitful collaboration with Prof. Louis Kauffman, the leading authority on this subject, and he continued, almost single-handedly, to publish the on-line Journal of Visual Mathematics. In fact, he did all of this in a lifetime full of physical challenges. There was nothing that could deter him and disturb his laser beam concentration and focus. However, with all of his adversities, he never once complained. It all became part of his special dance through life. Even through his final disease, his focus was more on sharing yet more of his extensive oeuvre than on the excruciating pain he was enduring. This world is richer for his presence and poorer now that he has departed.

I first met Slavik Jablan in the 1990s, and it was clear from the start that he had a new and different point of view about knot theory and indeed a different and artistic view of mathematics in general. He had worked in symmetry, ornaments, painting and design before coming to knot theory, and his vision of knot theory was suffused with the rich appearance of knotting and weaving in tapestry, painting and design, the use of knots both practical and decorative in rope-work and for ships and construction that extended back into antiquity. While for the rest of us, knot theory was a modern phenomenon that began in the 19th century, for Slavik, it was a mathematical phenomenon that had begun in the roots of civilization. I say a mathematical phenomenon, because it was mathematics in the patterns and calculations of weaving and painting and design. Knot theory became a chapter of systematized, algebraic and abstract mathematics only recently, but it had been part of a tradition that respected pattern and craft and practical calculation for long before that. This meant that Slavik’s view of knot theory was wider, more artistic and, at the same time, more computational than the rest of us. He was genuinely interested in how knots and links could fall into visual and recursively generated families. He was sensitive to the extraordinary combination of calculation and topological patterning that lay behind the abstract definitions that most of us explore. Consequently, he was willing to enter into computational investigations and conjectures about knots and links from all areas of the theory. He never stopped examining, from his point of view, any statement of relationships. This led him to make very fine conjectures (such as the Bernhard–Jablan conjecture about the unknotting number), and it made him an absolutely extraordinary collaborator. One could invent or discover some combinatorial property of knots and, the next day, send Slavik an account of the definition and ask some question about generating examples of a type or whether such and such a phenomenon might occur. He would immediately understand and put the matter to his computing system (LinKnot) and generate many examples, and the work and the conjecturing would go forward. He had a completely open mind, full creativity, devotion to art and mathematics, love of collaboration and love of friends and humanity. He was a person of value beyond words. We are going to miss him more and more as time goes on.

I first talked with Slavik Jablan at the International Centre for Theoretical Physics (ICTP) in Trieste in May 2009, where we co-organized, together with Louis Kauffman and Jozef Przytycki, the “Advanced School and Conference on Knot Theory and its Applications to Physics and Biology”. In the period prior to the meeting, we had discussed, over email, being the two local organizers. However, I had already, long before, heard of him and his ability to do programming and computations with knots, which would lead him to formulating deep conjectures.

At the ICTP, every evening of the meeting, we would sit with the four organizers at the terrace of the dinning cafeteria over a pitcher of wine, and we would see to organizational matters that needed attention. One evening, many of us played, on the spot, as actors at the improvised play “Dehn’s dilemma”. This was an idea I had been amusing myself with for a while, imagining topological surgery as medical surgery, of which I talked to Cameron Gordon early that evening with the pressing request that we do some kind of play. Cameron soon started forming a scenario in his mind, involving rational and irrational surgery and Dr. Dehn being an absurd doctor, which evolved into a superb, unforgettable comedy in the mind and hands of Colin Adams: “Unhappy solid torus wishes to become lens space, consults mad doctor who performs irrational surgery. The love interest of the torus falls for the figure 8 knot complement, and high drama occurs.” From YouTube: https://www.youtube.com/watch?v=UM-U5RE2mN0. I recall that Slavik enjoyed his role enormously, I think, being the solid torus, as well as the whole event. In September 2010, we co-organized the same team “Knots in Chicago”.

Two years later, I was asking him if he would be willing to help with a puzzling problem: with my collaborator Jesus Juyumaya from Chile, we had constructed an infinitum of knot and link invariants via the Yokonuma–Hecke algebras, which are quotients of the framed braid group over a complex quadratic relation. These invariants needed to be compared with known ones, especially with the Homflypt polynomial, but a direct comparison was not obvious. My student Konstantinos Karvounis and Michael Chmutov had created computational packages, so we started making computations (together with Sergei Chmutov). Slavik provided us immediately with several pairs of knots and links in braid form sharing the same Homflypt polynomial. We could quickly come to the idea that our invariants were no stronger than the Homflypt polynomial, but a theoretical proof was not in sight.

In April 2013, I visited him in Belgrade in order to look at the problem more systematically. There, I had the opportunity to meet his wife Jadranka, a music teacher, a wonderful person and a great cook. Their apartment, which had an artistic bohemian air, was full of Slavik’s amazing oil paintings and several rare and interesting artistic objects.

We started skyping with Konstantinos and making testing computations on knot and link families that Slavik had indicated. Soon, he was able to figure out some pattern. In September 2013, Slavik and Jadranka visited me in Athens, where, together with Konstantinos and Jesus, we managed to formulate our main conjecture: on knots, our invariants are topologically equivalent to the Homflypt polynomial. This was proven recently and will appear in a joint paper with his name on it. The conjecture was proven recently, and we even showed that on links, the behavior is different.

Slavik has been an excellent, tireless researcher and highly intelligent, with his own unique taste for mathematics and art; a good friend, a person with broad and deep human awareness, honest, open-minded and non-judgmental, in the company of whom one would feel a warm and calm light.

I first met Slavik at Knots in Hellas, Greece 1998. I remember him mostly as a strong proponent of the conjecture about the unknotting number, stating that under certain conditions, the unknotting number can be obtained from a minimal diagram, now known as the Bernhard –Jablan conjecture. The next time we met at Knots in Washington XVII in 2003, when he brought with him his student collaborator Radmila Sazdanovic. Radmila soon became my student, so following the example of Hugo Steinhaus, I can say that “Radmila was one of Slavik’s biggest mathematical discoveries”. One of Slavik’s greatest gifts was his passion of relating mathematics and art. This he advocated whenever I met him: in Trieste in May 2009 or, the last time, in India in December 2013. For all of this, he will be remembered!

I had the pleasure of being a student of Professor Slavik Jablan at the Faculty of Philosophy, Department of Mathematics at the University of Niš in 1990. Prof. Slavik Jablan also was my mentor for my Masters and PhD theses. During 25 years of collaborations, he became my dear friend. It was a great privilege to learn from him, not only mathematics and geometry, not only about symmetry and knots, but also about arts and artists, paintings and painters, about anthropology, archeology, architecture, ethnology, about movies, music and windsurfing.

Slavik Jablan was a brilliant mathematician and artist and, above all, a wonderful man, generous in shearing ideas, information, knowledge, books and graphics. It was not always easy to follow his quick mind nor keep track of his numerous ideas, amazing creativity and great intelligence, but it was a great honor to work with him and to be his friend. He always had new ideas about what we could do next and what we should write about and prepared new materials, workshops and projects. During all of these years, we worked on many papers and projects together. In the last two years, we were working on several projects. Our work on the paper “Classification of ornaments based on Serbian fresco medieval art” is especially precious for me, but also our work on the book Visual mathematics with Jay Kapraff, education material for the teachers included in the Tempus project “Visuality & Mathematics: Experimental Education of Mathematics through Visual Arts, Sciences and Playful Activities”, workshops and lectures.

We all were able to learn how to live and fight in spite of problems. In the last year, in spite of his illness, he has done so much: he published several significant papers on knot theory; he mentored Anna Zekovic PhD; actively took part as one of the leaders in the Tempus project; and had three exhibitions (first in May, then September and the last one in November 2014, at the RTS Gallery in Belgrade), which was followed by several lectures and workshops. He will be missed by all and remembered for his enthusiasm, cheerful spirit, vision, enormous creativity and great mind.

I met Slavik while I was writing the "matrurski" (end of high school) project and then, few years later, I was an undergraduate student in Belgrade, presenting at the DAAD workshop organized by Dr. Malkowski. Slavik asked if I was interested in working on a two-month project at the Mathematical Institute involving knots. I knew nothing about knots: he taught me. That two-month project turned into a two-year project that resulted in a software package “LinKnot” and a book to accompany it.

Knot theory ended up as a primary research focus in my PhD work and I had the honor of collaborating with Slavik until the tragic end of his life. I am grateful for his support and guidance over the years and the way his humor and wit kept me going when things were tough mathematically and otherwise.

Slavik’s view of mathematics was unique, innovative and insightful, much like his art, whether it was watercolors, oils or computer graphics. His passion and perseverance always were, and will always be, an inspiration to me. His friendship and brilliance will always be missed.

Slavik became one of my best friends ever since I met him for the first time; not only from the scientific point of view, because I always admired his new research results, especially on knot theory and its application in every type of design, but also from a human point of view, because he was so kind and generous with his numerous collaborators. I am 85 years old, a Doctor in Mathematics since 1958 and Full Emeritus Professor (2010) in the Faculty of Architecture, Design and Urban Planning (FADU) from the University of Buenos Aires, situated at the Universitary City, Buenos Aires, Argentina. The activities of the Centre of Mathematics & Design of which I have been the President since 1995, take place in FADU and my Laboratory of Mathematics & Design. Besides, since 2001, I have also been the President of the International Association of Mathematics & Design, whose main objective is to publish yearly the Journal of Mathematics & Design and to organize international conferences every three years. The last one was held at the Faculty of Architecture and Urbanism of the University of the province of Tucuman, Argentina. At this conference, Slavik Jablan was invited to deliver a regular lecture: “Plated Polyhedra: a knot theory point of view” (coauthors: Paulus Gerdes, Ljiljana Radovic and Radmila Sazdanovic). The proceedings of this conference were published as a Special Issue of the Journal of Mathematics & Design, Vol. 13. This was the VII International Mathematics & Design Conference (September 2013), and now, we are organizing the VIII one, which will take place at a beautiful and interesting site: Easter Island, 5–9 September 2016. Of course, I was preparing an invitation for Slavik Jablan to be a distinguished member of the Scientific Committee and deliver another of his wonderful talks. Unfortunately, God has won this career. However, his memory will be always with us!

I met Prof. Slavik Jablan over 15 years ago.

The mistral wind was blowing in the Bay of Kotor, and a group of windsurfers were surfing, with one leading, faster than any of the others. Impressed with his skill, I convinced him to teach me to windsurf.

It was painful for the first couple of days, and I barely remember whether I was falling or he was supporting me more. This aspect of our relationship has not changed in the last 15 years!

The moment I learned to windsurf, we switched to math. Just a year ago, when he found out about his illness, we stole a moment to be sad together, to gossip about doctors, but he stood up soon and made a new goal for us to finish my PhD thesis, with him by my side. The plan was to write a dissertation page per day; I gave him my promise: a new day, a new page!

Today’s page was hardest to write.

During the last year, he was sharing his precious time and strong motivation with me, as he always did. His huge energy and enthusiasm were an inspiration for the dissertation. Unselfishly, he continued with sharing his thoughts and ideas with me. I am grateful for his supporting me and my dissertation, till his very last day.

I defended my PhD on Thursday, on 26 February, the day my teacher passed away.

I know that I was lucky and honored having a chance to know him. I am proud for the time he spent with me and privileged to have learned from him. I have learned not to fall, now when it is hardest. I know that he would not like me to fail! Bravely, I will keep going, where we paused together for a moment, and continue with ideas planted by him.

Tailwind for you Slavik!

Prof. Dr. Slavik V. Jablan served as an Editorial Board member of Symmetry since 2009 and as its Editor-in-Chief since 2012. It was an honor to work with him, and he provided great support to the journal. MDPI and the editorial office send their condolences to his family and friends.