My sincere regards to his departed soul. May he rest in peace.

He was a visionary, who spent his last two plus decades trying to bring the subject of Algorithms to the students and faculty across India, to enhance their understanding and scholarship, as well as their research capabilities in the field. To this end, he organized more than 20 workshops in colleges, universities and institutions all over India. He started a new international conference CALDAM since 2015 to provide a forum for young and bright minds to publish high-quality research in the areas of Algorithms and discrete mathematics. He organized bilateral workshops to bring expert researchers in these areas from different countries to give talks geared towards teaching students topics in these areas. Over the years, he has organized Indo-Taiwan(2011), Indo-Israel(2013), Indo-Slovenian (2013, 2024), Indo-Czech, Indo-Hungarian, Indo-German(2016, 2017), Indo-Canadian (2018), Indo-Italian (2019), Indo-French (2020), Indo-Dutch (2023), Indo-Spanish (2025), Indo-Polish (2026) and a planned Indo-Austrian workshop for 2027. Rarely do we find individuals with this kind of dedication, and immense organization and people skills, to be able to successfully envision and run such workshops, conferences and the bilateral workshops of very high research quality, so that the students in India can learn the subject directly from experts. On a personal note, he was a wonderful person, ever accessible, a very insightful mentor with deep spiritual insights, and a guiding light. He will be deeply missed.

His legacy lives on in the countless lives he shaped and the knowledge he so freely shared.

​I had the distinct honor of working hand in hand with Prof. Ghosh when I served as the Organizing Chair for CALDAM 2024 at IIT Bhilai. Organizing a conference of that scale is a monumental challenge, but Prof. Ghosh’s presence changed everything. He did not just oversee from a distance; he immersed himself in the process. His continuous support, gentle reminders, and unmatched attention to detail made the immense task of organizing remarkably smooth. He monitored and offered invaluable suggestions on every minute arrangement, ensuring that the conference reflected the highest standards of academic excellence and hospitality.
​At the heart of his tireless efforts was a deep, enduring empathy for Indian students and research scholars. He was always profoundly concerned about the immense difficulties they faced in securing international travel grants to present their work abroad. It was this exact concern that motivated him to start CALDAM. He envisioned a world-class, reputable international platform right here in India, ensuring that our young researchers could engage with global mathematics and computer science pioneers without geographic or financial barriers.
​Now, as I step into the role of Program Committee Co-Chair for CALDAM 2027 at LNMIIT Jaipur, his absence is felt deeply. The blueprint he created for CALDAM, connecting young Indian minds with the global research community through bilateral preconference school remains our guiding star. As we look ahead to future editions of the conference he built from the ground up, we commit to honoring his incredible legacy by maintaining the rigorous and visionary spirit he instilled in us.
​Rest in peace, Prof. Ghosh. Your guidance stays with us.

Though my acquaintance with him is very short, I was impressed by his politeness and humility. He enlightened me with his short discourses on scientific and spiritual subjects. He departed untimely and abruptly. Pray for his eternal peace.

May his Soul Rest in Peace 🙏. We really miss him. His care, love and leadership really amazing starting from dinning hall to CALDAM PRESCHOOL CONFERENCE as well as main conference. Salute to Prof. Ghosh. His journey towards CALDAM CONFERENCE is always remember in everybody's heart.

My first meeting with Professor Subir Ghosh was at the ADMA conference held at Periyar University, Salem, in June 2009. I had spoken on betweenness and convexity in graphs; afterwards Subir came to me, asked thoughtful questions about my work, and began a conversation that would develop into a long and cherished professional friendship. From that first encounter his warmth, keen intellect, and generosity of spirit were immediately evident.

Later that year he visited the University of Kerala to deliver the Homi Bhabha Centenary Lecture (November 2009). Those who met him then remember not only the clarity of his exposition but the way he reached out to younger colleagues and students, encouraging them to pursue ambitious problems and to think deeply about foundational issues. Over the following years we met at many conferences, and one recurring topic was his desire to create a robust forum in India to nurture research and collaboration in discrete mathematics and algorithms—especially to support early-career researchers. This conviction shaped much of his subsequent work.

Subir translated that vision into action by organizing research-promotion workshops that combined rigorous technical sessions with mentoring and community building. One milestone was the workshop “Graphs and Geometric Algorithms,” held at the University of Kerala, Thiruvananthapuram, in 2014. That event brought together young researchers and senior experts and planted the seeds for a larger, more sustained forum. These efforts were instrumental in founding CALDAM.

The inaugural CALDAM took place at IIT Kanpur in 2015, with Prof. Sumit Ganguly and Ramesh Krishnamurthy serving as program chairs. Ever the decisive organizer and encourager, Subir then urged me (it felt less like a request and more like an affectionate order) to host the second CALDAM in Thiruvananthapuram. I had the privilege of organizing that meeting in 2016, which also included the Indo–Hungarian school, broadening the international reach of our community and exposing young Indian researchers to diverse perspectives and collaborations. Since then I have participated in every CALDAM, and in 2020 I served as program committee co-chair with Prof. Sandip Das for the conference at IIT Hyderabad.

Throughout these years I also served as a member of the Association for Computer Science and Discrete Mathematics (ASCDM) from its foundation. Working alongside Subir in ASCDM and in numerous CALDAM organizing and mentoring activities gave me a first-hand view of his exceptional leadership. He combined high standards of scholarship with a rare capacity to build consensus, to listen, and to motivate others. He cared deeply about maintaining scientific excellence while ensuring accessibility for those at the start of their careers.

Under his steady guidance CALDAM has grown into one of the leading international conferences in algorithms and discrete mathematics. Its evolution—into a forum recognized for quality research, rigorous peer review, and a welcoming environment for young researchers—is largely due to Subir’s vision, perseverance, and personal commitment. He was, in many people's eyes, the soul of CALDAM: its mentor, advocate, and principal source of inspiration.

I will always remember his kindness and his words of encouragement. One memory I cherish is his felicitation and blessings given to me on the occasion of my sixtieth birthday during CALDAM 2025 at PSG Tech, organized by R. S. Lekshmi. That moment captured Subir’s ability to celebrate colleagues as well as the community’s achievements, even as he urged us to aim higher.

Prof. Subir Ghosh passed away on 17 May 2026. His departure is an irreparable loss to CALDAM, to ASCDM, and to the broader discrete mathematics and theoretical computer science community in India and beyond. We mourn an outstanding scholar, a tireless organizer, and a generous mentor whose influence reached many lives and careers.

As we remember him, the most fitting tribute is to carry forward the work he championed: to preserve the scholarly rigor of CALDAM, to nurture young researchers, to promote collaboration across institutions and countries, and to sustain the welcoming intellectual community he built. In doing so we honor his memory and keep alive the values he embodied—curiosity, integrity, generosity, and dedication to the next generation of researchers.

I pay my humble respects to the memory of Prof. Subir Ghosh and pray for the eternal peace of his noble soul. May his ideas and his mentorship continue to inspire us, and may CALDAM remain a living testament to his vision.

I met Subir in early 2019, we had some nice Indo-French project that led to joint publications. This was the starting point for further collaborations with multiple people across India. I enjoyed hosting him and his wife in Clermont-Ferrand in 2021.

Subir was a great community-builder for students and academics, and I am happy to regularly participate in CALDAM in the last few years, a conference series which he helped create and animate with great energy, and a good sense of humour!

He will be missed, but his scientific legacy will remain.

My sincere condolences to his family, friends and colleagues.

Subhir had visited CUSAT a couple of years ago to deliver Homi Bhaba memorial lecture sponsored by
sponsored by DAE, if my memory is correct. He gave the lecture in our computer science department.
We then travelled as an Indian team for the biennial Indo- Taiwan conference held
in Taiwan. Our friendship grew due to some common academic interests.
. I was invited to the CALDAM 2019 held at IIT Kharagpur and Prof. Sudepkumar Pal
and myself edited the Springer Proceedings. He was a great research
er with strong commitments. His demise was quite shocking. I knew his
demise by chance through the fb post of our common friend Parthasaradhi Mukhopady
a. My Pranams 🌹

It is very shocking news for me. It is a huge loss to all of us. People will always remember him for his remarkable contributions to the fields of computational geometry and discrete algorithms in India. He inspired and motivated a large number of researchers working in these areas. I pay my sincere respects to his departed soul. May he rest in peace.

Subhir had wonderful ideas for guiding Indian combinatorics in the right direction, and a talent for implementing these ideas. We worked together at the Indian-Polish conference three months ago. He managed and directed the organization with a strong hand at every stage, remaining fully committed to science. This is an irreplaceable loss for Indian discrete mathematics. He was a dedicated mentor who inspired countless young scientists to pursue their passions.
Honor his memory!

Subhir had wonderful ideas for guiding Indian combinatorics in the right direction, and a talent for implementing these ideas. We worked together at the Indian-Polish conference three months ago. He managed and directed the organization with a strong hand at every stage, remaining fully committed to science. This is an irreplaceable loss for Indian discrete mathematics. He was a dedicated mentor who inspired countless young scientists to pursue their passions.
Honor his memory!

I had the honor of meeting this great man with a wonderful personality at CALDAM 2024. I truly enjoyed his presence, and he is someone who has stayed in my thoughts ever since.

I met Dr. Subhir Ghosh at CALDAM 2024. I had attended the conference on a whim. Dr. Subir Ghosh treated me with kindness and warmth despite me being someone new to the CALDAM scene. He also invited me to participate more in upcoming CALDAM conferences. Our meeting was brief, but one cannot forget his gentle exhortations. His loss is a great one but his legacy will live on.

As an RKMVERI student (2023-25), I feel incredibly fortunate to have been taught Approximation & Online Algorithms and Advanced Algorithms by Subir Sir.

His classes were truly some of the best of our lives—every single student would show up, resulting in nearly 100% attendance because no one wanted to miss a moment of his inspiring teaching style.

He guided us deeply, not just academically, but also as a mentor for life.

Attending the CALDAM conference in Coimbatore was a memorable experience that showed his incredible legacy in action.

We will always miss you, Sir. Rest in peace. 🙏

It is very difficult for me to write a tribute message for Dr. Subir Ghosh, our beloved Subir Da, whom I had known since the late 1990s. Like many academicians across the country, I had the privilege of working closely with him at several academic conferences and schools organized throughout India. Over the years, I witnessed his extraordinary ability to organize such events while maintaining the highest standards of academic excellence and hospitality.

Subir Da was a dedicated researcher with deep commitment to his field. He worked tirelessly to introduce Computational Geometry Algorithms and Discrete Mathematics to students and faculty members across the country, helping them develop a stronger understanding of these subjects and encouraging high-quality research in these areas.

He was deeply aware of the immense challenges faced by Indian students and young researchers in achieving international standards of research because of financial and other constraints. With remarkable vision and determination, he played a pioneering role in establishing CALDAM as an internationally respected academic platform. This contribution alone will ensure that he is remembered with gratitude and respect by countless research scholars in our country.

Behind his seemingly stern exterior was a deeply dutiful, responsible, and caring person. His untimely departure is not only a great loss to the research community of our country, but also a profound personal loss to me.

Saying goodbye truly hurts. Memories can never replace your presence.

Rest in peace, Subir Da.

When I was an undergraduate student at IIIT-Hyderabad, I got my first chance to attend a workshop on Graph Algorithms held at IISc. Prof. Subhir Ghosh was the main organiser of this workshop. The workshop was a very important event in my research career. For the first time, I got exposed to leading experts in theoretical computer science, and got to experience first-hand how high quality algorithm talks are delivered. I have very fond and exciting memories of the workshop till date!

I have known Prof. Subir Ghosh since 2015 when I met him during the first CALDAM at IIT Kanpur. Later we had a Indo-French project together. Our project was instrumental in organising the Indo-French school in CALDAM 2020, and I suppose, we started becoming closer since then. He wanted me to get more involved with CALDAM, and also organize it once (which we did very successfully in 2026). During many of my conversations with him I understood his motivation for organizing CALDAM was to create a venue for Indian students to gain international level exposure in India, which I solely respect and appreciate. I feel CALDAM is one of his biggest contributions made to the Indian discrete mathematics community.

I became personally close to him. I still remember waking up to his WhatsApp messages "call me when free", and speaking to him very early in the morning (sometimes even 6.30am!). Even though I never wrote a paper with him, we discussed several academic aspects including his ideas about CALDAM's future. In this process, I got to know him closely. The one thing I liked the most about his personality is: he was absolutely transparent and honest. He didn't have any hidden agenda, whatever he thought, he spoke. Since I try to be the same, our conversations were always direct, to the point, and honest, and I enjoyed that very much.

Recently, I also started seeing the softer core of his personality. I still remember how he affectionately patted my student Tapas as he got less sleep due to CALDAM organization. I will miss his humourous comments.

Overall, I am deeply saddened and shocked to learn this horrible news. The memories of hosting him at my house iin February is still fresh, and it took me some time to accept his passing away. It still feels that he is just one call away. May his soul rest in peace.

Very sad to hear this. SK Ghosh was a true friend of Algorithmic Graph Theory, and I enjoyed his hospitality at CALDAM and other occasions in India. He helped our entire community and will be remembered.

Subir was a wonderful person. Both my wife and I enjoyed the conversations with him, and are grateful for his hospitality at CALDAM. I also owe him the invitation to choose the speakers for the Austro-Indian preschool of Caldam 2027. I will miss him a lot and hope that CALDAM will survive.

My memories with Prof. starts with the internship days at TIFR under his mentorship. I tried to visit him on a weekend when I reached Mumbai. He yelled at me on the phone that it is a holiday for him. I was very anxious and worried that I irritated him till I met him in his office the next day. I still remember waiting before his office; he was walking through the corridor towards me and called out my name joyously, "You might be Divya; at last we met! "That is when I realized he is very approachable and a genuine personality. The internship lasted for four months and he gave me the freedon to work on my own and guided/ corrected me, but always kept me enough space for my own exploration and thoughts. It was a great experience. I also had the opportunity to be in classes on approximation algorithms.

Later I had opportunities to meet him at IIT Kanpur for the CALDAM conference. He cared for the small things. I was carrying my two-year-old baby with me to the conference. When he saw it was cold outside, he immediately came to me and advised that I should cover the baby's ears and head. It was least expected from a senior professor like him. But as others already mentioned here, he was very genuine and caring.

I didn't have opportunities to work with him after the internship, but he was the reason that I came to graph theory research and academics. Thank you, Professor, for being the guiding light. May your soul rest in peace! Om Shanti!

Ever since my first visit to the Tata Institute in Mumbai, Subir took charge of my logistics—booking my tickets and arranging for me to "preach" at IITs, universities, and institutes across the country. He welcomed me into his wonderful family and introduced me to many excellent mathematicians and computer scientists. Subir had fascinating views on just about everything; arguing with him about science, history, religion, and the future was a true intellectual pleasure. He was a deeply affectionate yet passionate man who invested immense time and energy into uplifting his department, his institute, and the advancement of algorithmic theory and discrete mathematics in India. Never one to shy away from confronting powerful authorities or obstacles for a good cause, he was an unstoppable force, a brilliant organizer, a loyal friend, and a kindly spirit. His absence leaves a void that will be hard to fill.

I first met Prof. Subir Ghosh at CALDAM 2016 in Trivandrum, and remained in touch with him ever since. He played a pivotal role in bringing together researchers from across the country in algorithms and discrete mathematics, building a true community. I had the privilege of working closely with him while organizing CALDAM 2019, and was always struck by how clearly and systematically he spoke — a reflection of his great clarity of thought. His warmth and vision will be deeply missed.

A tribute like this does not seem enough for the loving father that he was, but it is the least that I can do. He was a guardian angel and an example to follow in many aspects of life. Most of all, I saw in him someone who saw strangers as friends, friends as family, and family as something to never ever give up on. He was also a willing listener to ideas both fashionable and otherwise. He was a safe space for anyone unconventional and a friend to those who needed one the most. I hope he's in a better place now.