Stretchings
Finkel, Olivier ; Ressayre, Jean-Pierre
HAL, hal-00103669 / Harvested from HAL
A structure is locally finite if every finitely generated substructure is finite; local sentences are universal sentences all models of which are locally finite. The stretching theorem for local sentences expresses a remarkable reflection phenomenon between the finite and the infinite models of local sentences. This result in part requires strong axioms to be proved; it was studied by the second named author [J.S.L. 53, No. 4, p. 1009-1026]. Here we correct and extend this paper; in particular we show that the stretching theorem implies the existence of inaccessible cardinals, and has precisely the consistency strength of Mahlo cardinals of finite order. And we present a sequel due to the first named author: (i) decidability of the spectrum Sp( phi ) of a local sentence phi, below omega^omega ; where Sp( phi ) is the set of ordinals alpha such that phi has a model of order type alpha; (ii) proof that beth_omega =sup { Sp( phi ) : phi local sentence with a bounded spectrum}; (iii) existence of a local sentence phi such that Sp( phi ) contains all infinite ordinals except the inaccessible cardinals.
Publié le : 1996-07-05
Classification:  [MATH.MATH-LO]Mathematics [math]/Logic [math.LO],  [INFO.INFO-LO]Computer Science [cs]/Logic in Computer Science [cs.LO]
@article{hal-00103669,
     author = {Finkel, Olivier and Ressayre, Jean-Pierre},
     title = {Stretchings},
     journal = {HAL},
     volume = {1996},
     number = {0},
     year = {1996},
     language = {en},
     url = {http://dml.mathdoc.fr/item/hal-00103669}
}
Finkel, Olivier; Ressayre, Jean-Pierre. Stretchings. HAL, Tome 1996 (1996) no. 0, . http://gdmltest.u-ga.fr/item/hal-00103669/