Cosmological constraints from lensing statistics and supernovae on the cosmic equation of state

We investigate observational constraints from lensing statistics and high-z type Ia supernovae on flat cosmological models with nonrelativistic matter and an exotic fluid with an equation of state, p(x)=(m/3-1)rho(x). We show that agreement with both tests at the 68% confidence level is possible if the parameter m is low (m less than or similar to 0.85) and 0.24 less than or similar to Omega(m0)less than or similar to 0.38 with lower values of Omega(m0) corresponding to higher m. We find that a conventional cosmological constant model with Omega(m0)similar or equal to 0.33 is the best fit model of the combined likelihood. [S0556-2821(99)04410-0].