BSL
2006
14 years 2 months ago
2006
We show that each of the five basic theories of second order arithmetic that play a central role in reverse mathematics has a natural counterpart in the language of nonstandard ari...
CSL
2007
Springer
14 years 8 months ago
2007
Springer
In 1973, Parikh proved a speed-up theorem conjectured by G¨odel 37 years before: there exist arithmetical formulæ that are provable in first order arithmetic, but whose shorter ...