Título inglés |
On Ø-definable elements in a field |
Título español |
Elementos Ø-definibles en un campo. |
Autor/es |
Tyszka, Apoloniusz |
Organización |
Tech. Fac. Hugo Kollataj Univ., Cracovia, Polonia |
Revista |
0010-0757 |
Publicación |
2007, 58 (1): 73-84, 17 Ref. |
Tipo de documento |
articulo |
Idioma |
Inglés |
Resumen inglés |
We develop an arithmetic characterization of elements in a field which are first-order definable by a parameter-free existential formula in the language of rings. As applications we show that in fields containing any algebraically closed field only the elements of the prime field are existentially Æ-definable. On the other hand, many finitely generated extensins of Q contain existentially Æ-definable elements which are transcendental over Q. Finally, we show that all transcendental elements in R having a recursive approximation by rationals, are definable in R(t), and the same holds when one replaces R by any Pythagorean subfield of R. |
Acceso al artículo completo |