I met Karl at UUCC about 10 years ago - he always shared a warm smile and greeting with me, and I quickly found him to be a quiet thinker with a kind and gentle soul.

The loss of someone who wasn't yet finished living is what makes his passing so shocking.  I'm so used to seeing all his Facebook updates with pictures of his latest exciting  hikes and travels with Susan and/or Eric.  

My deepest sympathy to Susan and Eric.  What an amazing person.

I first met Karl fifty years ago when he took a couple of philosophy classes from me at the University of Colorado. He wasn’t just the best student in whatever class he was in—he was absolutely brilliant. I thought that he could have a stellar career in philosophy, and I told him so. But Karl had many interests besides philosophy. He was a strong math student and took lots of math courses (almost enough for a major, as I recall). He was a fine chess player—far too good for me, I soon discovered. Classical music was another of his loves, and for a time after graduation he studied music theory.

I was really just a kid myself back then, and Karl and I soon became fast friends. We hiked together, listened to classical music together, and sometimes partied together. Karl took me rock-climbing, and Barbara and I went camping with him. It was a special time in my life and Karl was a big part of what made it special.

Karl never forgot me, nor I him. We got together many times over the years, sometimes for extended visits. Just over two weeks ago, Karl and Susan welcomed us (once again) as house guests, this time in Frisco CO. Karl took us on several hikes, and we had wonderful conversations about all sorts of things. On the evening of August 9, the four of us watched a film together and brain-stormed about it. During our visit, Karl told us about his current plans and projects, and especially about the book that was to be his legacy. As I understood the project, he wanted to show how artificial intelligence could be used to make the law more accessible to people of limited means.

During that visit, Karl made quite a point of thanking me for what I had done for him fifty years ago. If, indeed, I helped Karl believe in himself and in his own future, then it is the best thing I have ever done. But as I told him, when I shook his hand for the very last time, he had repaid me many times over.

The breadth and brilliance of Karl’s intellect, his sparkling wit, and his personal warmth and generosity are unique in my experience. His innumerable kindnesses to me and to Barbara over the years bring tears to my eyes, and I am profoundly grateful for his loyalty and friendship. I love him dearly and I mourn this terrible loss.

Karl was a close colleague for 14 years at MITRE. I had talked to him in Colorado on Weds a few days before he passed.  When I was notified by a colleague that Friday, I was shocked and remain so. It is hard to believe because he sounded fine, he sent me an email after the call about an idea we were working on and then he was gone.  Just like that.  

We spun up many ideas together, some a little crazy but some were pretty interesting and some were inspiring.  I always felt like we were perpetually looking for funding.  I called him the money whisperer because his intellect and charm were a winning combination when hunting for seed funding.  He always seemed to find it.

We often talked about law and technology -- in New York, Chicago, Montreal at the Stanford Codex and a host of other spots.  He was widely respected in those circles, and I have talked to many of our colleagues who were deeply saddened.  Most said the same thing, "he was such a nice guy." 

He was an intellectual, witty but with a dry sense of humor.  He always got the joke, and it was easy to make him laugh.

Karl was a mentor to many at MITRE and I think that was something he truly enjoyed.  He got a lot of energy from it.

We submitted a non-provisional patent application with our team for FOIA Assistant a few months ago and Karl told me then that he was looking forward to being "an inventor."  The truth is that he was always inventing and writing.  We wrote a number of articles together. He preferred long technical articles, but he also appreciate more topical pieces as well.

He looked forward to vacations and hiking with Susan every summer in Colorado and was looking forward to more trips that mixed adventure and learning.  He often talked about his son and was very proud of his work and he was close to his daughter-in- law as well. 

I will miss Karl.  I cannot remember a week, in a very long time, when I have not spoken with him about something -- an idea, an article, AI, something in the news, etc.  He was a wonderful colleague and friend and I am sad that he is gone.  He was working on a book and had more to say and I am hopeful that enough was complete so that he can have the final word.

Godspeed and rest in peace my friend.  It won't be the same without you.

Brad Brown

Karl took me under his wing when I first started at MITRE fresh out of graduate school. His interest in the cross section of AI and Human Centered Engineering (HCE) was infectious. We often found ourselves over time in our one-on-one meetings chatting about his other AI projects and the applicability of HCE, which then somehow would evolve into chats about his recent adventures, our families, or my travel aspirations. Before we knew it, we were 20-30 minutes overtime. This tended to happen more often than not. 

He advocated for HCE, a field that many still are not familiar with, in each of his AI projects and fought for my spot on these teams. He even went as far as to send kind notes bragging about my work to my father, who he knew professionally from his time at MITRE. He was kind-hearted, witty, and a positive light during challenging or frustrating times.  He gave me opportunities that many would not have offered a fresh graduate, and he took the time to get to know me on a personal level over the years. I knew I could look to him for advice, mentorship, and an optimistic perspective that is rare to find these days. I will miss him dearly. 

I'm just totally shocked and saddened by Karl's passing.   Such a wonderful soul?   He touched my life in such a positive way and I'm so grateful I got to know and work with him.  Deepest condolences to Susan and Eric and his extended family. 

He lives behind such a great legacy.   Such a wonderful person who contributed so much to technology and science.

He will be missed.