  The purpose of this paper is to develop a unified a posteriori method for
verifying the positivity of solutions of elliptic boundary value problems by
assuming neither $H^2$-regularity nor $ L^{\infty} $-error estimation, but only
$ H^1_0 $-error estimation. In [J. Comput. Appl. Math, Vol. 370, (2020)
112647], we proposed two approaches to verify the positivity of solutions of
several semilinear elliptic boundary value problems. However, some cases
require $ L^{\infty} $-error estimation and, therefore, narrow applicability.
In this paper, we extend one of the approaches and combine it with a priori
error bounds for Laplacian eigenvalues to obtain a unified method that has wide
application. We describe how to evaluate some constants required to verify the
positivity of desired solutions. We apply our method to several problems,
including those to which the previous method is not applicable.
