“Heydar Radjavi is seventy years old? Impossible; he’s too vigorous!” “He can’t be seventy; he’s too productive!” “Seventy? That can’t be true; he’s too good-looking!” It is true; vigorous, productive and good-looking as he is, Heydar Radjavi is seventy years old as of January 17, 2005. Most of us slow down, at least a bit, as we enter our sixties. Not Heydar. As his list of publications establishes (see the end of this article for complete references to his research papers to date, followed by a list of his books), Heydar’s productivity is an increasing function of his age.
 

Click the following links to download the Persian (Farsi) and English proceeding of SLAA-12:
 

مجموعه مقالات فارسی

Proceeding of SLAA-12

Portraits of Heydar Radjavi:

The following paragraph is a description of the two portraits from SLAA-12 proceeding:
'Finally, special thanks go to the artists who brought the ideas into the two beautiful portraits of Heydar, one of them is an oil painting and the other is a typography portrait of him, in which the words are mostly borrowed from a paper from a Special Issue of Linear Algebra and its Applications in honor of Heydar's 70th birthday.
 R. Bhatia, M. Omladic, P. Rosenthal and P. Semrl, A survey of Heydar Radjavi, Linear Algebra and its Applications 383 (2004) 1–15.'

_____________________________________________________
Messages in honour of Heydar Radjavi:
_____________________________________________________

---

Peter Rosenthal
Emeritus Professor of Mathematics,
University of Toronto, Canada.

The third Iranian Seminar on Linear Algebra and its Applications, held in Kerman in December 2004, was in honour of the seventieth birthday of Heydar Radjavi. It is fitting that the twelfth such Seminar is also in Heydar's honour. Issue 383 (2004) of the journal Linear Algebra and its Applications was in Heydar's honour.  I was co-author (along with Rajendra Bhatia, Matjaz Omladic, and Peter Semrl) of the Preface to that issue, titled A Survey of Heydar Radjavi. The Preface contains a brief description of his life and an overview of his mathematics up until 2004. It begins as follows.

Heydar Radjavi is seventy years old? Impossible; he's too vigorous! He cant be seventy; he's too productive! Seventy? That can't be true; he's too good-looking! It is true; vigorous, productive and good-looking as he is, Heydar Radjavi is seventy years old as of January 17, 2005. Most of us slow down, at least a bit, as we enter our sixties. Not Heydar. As his list of publications establishes (see the end of this article for complete references to his research papers to date, followed by a list of his books), Heydar's productivity is an increasing function of his age. As his many collaborators know, it is a great pleasure to work with Heydar. He is a very talented and knowledgeable mathematician. He loves thinking and talking about mathematics and working with others. His enthusiasm never seems to wane, even when numerous attacks on a problem fail, and even on those occasions when an unfillable gap is found in what the collaborating group had thought was a really nice discovery. He is helpful and pleasant to everyone, and is not at all competitive. Heydar is almost always in great spirits: the joy he finds in mathematics is part of his overall joy in life. He is one of the few people to whom the word ebullient is truly applicable. His lectures are wonderful: they are invariably very interesting and clear, and peppered with Heydar's special humor. He is, overall, the nicest kind of human being. It is a great pleasure to visit Heydar and his wife Ursula. In particular, they are great cooks: A nontrivial corollary of working with Heydar is the opportunity to sample the delicious Iranian meals he and Ursula prepare. This survey consists of a brief look at Heydar's background followed by discussions of a few of the highlights of his mathematical work.

It is hard to believe but, over the time period from Heydar's seventieth birthday to today, Heydar's productivity has continued to be an increasing function of his age. Moreover, he is still ebullient.

---

_____________________________________________________
 

Mitja Mastnak
Professor of Mathematics
Saint Mary's University, Canada.

It is important to acknowledge and celebrate the exceptional contributions of individuals who made significant advancements in their fields and also enriched the lives of everyone around them; Heydar Radjavi is undoubtedly one of them. 

Heydar's influence on my professional journey and my life in general cannot be overstated.  I first briefly met him during his visit to Matjaz Omladic, my honours thesis supervisor, at University of Ljubljana in the 1990's.  Even though I was a lowly undergrad, Heydar had time to have a nice chat we me.  We talked mostly about mathematics, but also discussed some worldly things.  For example, Heydar's underappreciation for the amount of egg yolk in omelets in his hotel. 

When I started my graduate studies at Dalhousie, I had the privilege of taking the last course he ever taught there: a reading course on simultaneous triangularization. Heydar also ran an informal linear algebra seminar that allowed me to join the fellowship of Heydar's coauthors even before I graduated. 

Then there were Tuesday lunches and, when Heydar had visitors, lavish dinners at the Radjavi household.  Heydar taught me how to properly cook rice.  I was able to return that favour about two decades later when my daughters taught him how to make tacos out of the weeds in our back yard. 

During a crucial time when I was seeking employment, Heydar extended a helping hand and offered me a position as a postdoctoral fellow at the University of Waterloo.  I will always be grateful for his support and the trust he placed in me. Working alongside Heydar Radjavi has been a truly transformative experience.  Even in projects where he wasn't a direct coauthor, his influence has been immense. 

Recent pandemic also has some good side-effects: I now get to Zoom with Heydar every week. Mathematicians have one of the best jobs in the world, but those few of us (actually not quite so few) that collaborate with Heydar are fortunate indeed. I was thinking hard about my favourite joint project with Heydar and came to the obvious conclusion: it is our next one. Well, probably the one after that. 

In Halifax, July 14, 2023 
Mitja Mastnak
_____________________________________________________






Dear Heydar, 

It has been a pleasure to know you, discuss math with you, and to call you my friend. In particular during the past 20 years, during your 'retirement'', you have been anything but retired. 

Your continued interest in mathematical questions is a source of inspiration to me as a newly 'retired'' person. 

Also we have had many interesting conversations over a Friday get togethers, even in the past three years thanks to Zoom! 

I wish you well on the occasion of this conference. 

Regards, Ken
_____________________________________________________


Bob Pare
Emeritus Professor of Mathematics 
Dalhousie University, Canada.  



         Heydar Radjavi

There once was a prof from Tabriz
Who said solving problems' a breeze
Just make a big matrix
Then use everyday tricks
You can prove whatever you please

  Cheers,

   Bob

_____________________________________________________


Chelluri Sastri
Emeritus Professor of Mathematics
Dalhousie University, Canada.  








 Heydar and I have been friends since 1980, and I must say that that friendship has sustained me through all these years. What we have in common is a love of reading and walking; he is also a writer who has written two memoirs; although I haven't published anything, I have written a bit.

Heydar and I have only one joint paper, in which he helped answer a question of mine in the area of unobserved probability. What impressed me most was his showing that an example I had come up with, with some help from my late son Raju, encapsulated everything that the general case entailed. Remarkable!

Regards and best wishes,

Sastri

_____________________________________________________

Yuanhang Zhang
Assistant Professor of Mathematics
Jilin University, China.








I got to know Professor Heydar Radjavi in 2005 when I prepared my undergraduate thesis. My supervisor gave me a Chinese translation of his famous book “Invariant Subspaces”, co-authored with Professor Peter Rosenthal. This book introduced me to the fascinating field of operator theory.

In 2019, I had the opportunity to visit Professor Laurent Marcoux and work with him and Professor Heydar Radjavi. I often attended the long-standing Tuesday Lunches, where I learned math and other interesting stories from Heydar. I have many precious memories of that time!

After returning to China, we continued to have regular weekly Zoom meetings. Sometimes, Laurent or I would find results in the literature that may be useful for our project, and Heydar would say: “That’s a nice result! Who proved it?” We would reply: “Haha, you did!” Yes, Heydar has so many influential and substantial results, and (I bet that) he will keep doing math even more productively. I am honored and grateful for the collaboration with Heydar and Laurent, which has influenced my career. 

Thank you!

_____________________________________________________