Bianchi Type-II Inflationary Models with Stiff Matter and Decaying Cosmological Term

We deal with Einstein's field equations with a time-decaying cosmological term of the forms (i) Λ = β(ä/a) + α/a² and (ii) Λ = α/a², where a is the average scale factor of the universe, α and β are constants for a spatially homogeneous and anisotropic LRS Bianchi type-II spacetime. Exact solutions of the field equations for stiff matter are obtained by applying a special law of variation for the Hubble parameter. Anisotropic cosmological models are presented with a constant negative deceleration parameter which corresponds to the accelerated phase of the present universe. The cosmological constant Λ is obtained as a decreasing function of time that is approaching a small positive value at the present epoch, which is corroborated by the consequences from recent supernovae Ia observations. The physical and kinematical behaviors of the models are also discussed.