In October 1999 I started attending seminars on information technology in mathematical education, organized at Kharkiv State Pedagogical University by Sergey A. Rakov. There I met Kirill Osenkov, a programmer, who also turned out to be a first-year student at our Department (Kharkiv National University).

Soon our seminar evolved into a development team, where we started creating a package for computer support of school geometry course. Since then we have been working together with Kirill in a team, leaded and inspired by Sergey Rakov – Kirill's mentor and supervisor. Kirill was responsible for the interactive computer software design and programming. His task was not an easy one: he had to design and develop an interactive modeling environment for plane geometry, that would suit both our methodological requirements and needs of mathematical educators and students. Nevertheless Kirill perfectly coped with this work, showing enthusiasm and often proposing and doing more than was intended.

Kirill is a friendly and easy-going person. He has very positive personal attitude towards people and I think that most people who know him, like and respect him, just as we all do. It is a pleasure working with Kirill - he fountains with energy, enthusiasm, bright ideas and non-standard workarounds in complex situations. He is a fruitful idea generator, always showing creative approach and active participation in common design process and discussions. When the problem is being posed, Kirill always shows insight into the core problem, taking into consideration all requirements and conditions and often proposing his own vision, recommending solutions and workarounds. He is a skillful and inventive programmer, providing quality realization and ingenious solutions. He is very responsible and does a lot to provide maximum development quality – carrying out thorough and extensive testing, carefully questionning us on how to improve the functionality and user interface, attentively listening to all our (numerous!) advice, comments, critics and requests. He made most of our "dreams" come true.

As a result, in summer 2002 DG Dynamic Geometry package was the first Ukrainian educational software to receive official certification and approve of Ministry of Education of Ukraine. Kirill played a crucial role to achieve this and I highly recommend him as a valuable specialist – professional programmer and applied mathematician.

Victor T. Lisitsa