1. As a matter of mathematical logic , no code can achieve all three. 2. Mathematical logic generally does not countenance explicit reference to its own sentences.3. He specializes in mathematical logic , particularly set theory, and theoretical computer science. 4. He is the author of numerous papers on mathematical logic and linguistics. 5. He discovered mathematical logic , his chosen field, while visiting G�ttingen in 1929. 6. Paul Halmos described it as a technical special development in mathematical logic . 7. His main research areas are mathematical logic , complexity theory and proof complexity. 8. Pure set theory is one of the four parts of mathematical logic . 9. He is currently a professor of mathematical logic at the University of Oxford. 10. In 1967 Vopnka became head of the newly established Department of Mathematical Logic .