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Vassil Vassilev

Princeton University



Dr. Vasil Vassilev is a researcher in the field of software engineering with Princeton University. His main research interests are in the field of programming languages and systems for processing large amounts of data.

Vassil is a co-author of the interactive C++ interpreter, Cling, which facilitates the processing of scientific data in the field of high energy physics (HEP) and beyond. The interpreter is an essential part of the software tools of the LHC experimental program and was part of the software used to detect the gravitational waves of the LIGO experiment. As of today, Cling has helped to analyze 1 Exabyte physics data, which is the basis for the publication of over 1000 scientific publications in various scientific journals and conferences such as Nature, Physics Letters and Physical Review Letters. For the last 10 years he has been involved in the modernization of the specialized software package for processing exabytes of scientific data called ROOT. The software package is the basis of data analysis in experimental physics, playing a significant role in the discovery of the Higgs boson from the Large Hadron Collider (LHC) and the large cavity in the Pyramid of Cheops. Led the integration (and occasional enhancements) of the C++ Modules feature in HEP.

He is responsible for the participation of Bulgaria in the ISO C++ standards committee and JTC1/SC22 since 2015. Code owner of Incremental compilation, REPLs and clang-repl in the Clang compiler. Works actively in the field of Data Science and a passionate promoter of interactive, differentiable C++ for Data Science. Authored the C/C++ automatic differentiation library, Clad, which enables efficient syntheses of derivatives and gradients.

Currently a Research Software Engineer with Princeton University, leading the efforts in compiler-based automatic differentiation with C++ ( OAC-2311471 ). Worked for CERN, Switzerland and FermiLab, USA.

Project interests

Vassil runs the initiative which primarily focuses on establishing a dynamic and collaborative hub, bringing together researchers, practitioners, and educators united by their enthusiasm for foundational software tools. The group interests are in interpretative C/C++/CUDA, automatic differentiation tools, and C++ language interoperability with Python. Members of the group develop the first C++11-complient interpreter Cling, its successor ClangRepl and the pioneering compiler-based source transformation automatic differentiation tool Clad.

Their impact extends to the LLVM project, with contributions that enhance the landscape of compiler technology. Moreover, the group plays a pivotal role in maintaining core infrastructure for exascale data analysis within the high energy physics domain, courtesy of their involvement in the ROOT project.

Vassil is interested in collaborating in the area of programming languages, automatic differentiation and exascale data science. In addition, he always looks for talented students with cool ideas to help them on their way to becoming successful professionals.

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