Energy constraints and F ( T , T G ) $F(T,T_{G})$ cosmology

T F S C M T  G T  F

In this paper, we extend our ideas on model transformations as functors discussed in the previous issue and embed this concept into the framework of graph transformation systems. We show that under certain restrictions of the rules model transformations by graph transformation are functors.

f(T) teleparallel gravity and cosmology.

Over recent decades, the role of torsion in gravity has been extensively investigated along the main direction of bringing gravity closer to its gauge formulation and incorporating spin in a geometric description. Here we review various torsional constructions, from teleparallel, to Einstein-Cartan, and metric-affine gauge theories, resulting in extending torsional gravity in the paradigm of f ...

OSCILLATORY AND ASYMPTOTIC BEHAVIOR OF dx dt + Q ( t ) G ( x ( t − σ ( t ) ) ) = f ( t )

Consider the equation dx dt +Q(t)G(x(t− σ(t))) = f(t) (∗) where f, σ,Q ∈ C([0,∞), [0,∞)), G ∈ C(R,R),G(−x) = −G(x), xG(x) > o for x 6= 0, G is non-decreasing, t > σ(t), σ(t) is decreasing and t − σ(t) → ∞ as t → ∞. Whenf(t) ≡ 0, a sufficient condition in terms of the constants k = lim inf t→∞ Z

Cosmology of F(T) Gravity and k-Essence

Noether symmetry approach in f(T, B) teleparallel cosmology

We consider the cosmology derived from f(T, B) gravity where T is the torsion scalar and [Formula: see text] a boundary term. In particular we discuss how it is possible to recover, under the same standard, the teleparallel f(T) gravity, the curvature f(R) gravity, and the teleparallel-curvature f(R, T) gravity, which are particular cases of f(T, B). We adopt the Noether Symmetry Approach to st...