Fernández Jambrina, LeonardoGonzález Romero, Luis Manuel2023-06-202023-06-201999-030264-938110.1088/0264-9381/16/3/023https://hdl.handle.net/20.500.14352/59737© Amer Physical Soc. The present work has been supported by Dirección General de Enseñanza Superior Project PB95-0371. The authors wish to thank F. J. Chinea and M. J. Pareja for valuable discussions.In this paper a new formalism based on exterior differential systems is derived for perfect-fluid spacetimes endowed with an abelian orthogonally transitive G_2 group of motions acting on spacelike surfaces. This formulation allows simplifications of Einstein equations and it can be applied for different purposes. As an example a singularity-free metric is rederived in this framework. A sufficient condition for a diagonal metric to be geodesically complete is also provided.engjournal articlehttp://dx.doi.org/10.1088/0264-9381/16/3/023http://iopscience.iop.orghttp://arxiv.org/abs/gr-qc/9812039open access51-73Inhomogeneous cosmologiesSingularityFísica-Modelos matemáticosFísica matemática