We consider the equation
Δu − V (x)u + W(x)up = 0 and its parabolic counterpart in noncompact manifolds.
Under some natural conditions on the positive functions V and W, which
may only have ‘slow’ or no decay near infinity, we establish existence of
positive solutions in both the critical and the subcritical case. This leads to the
solutions, in the difficult positive curvature case, of many scalar curvature
equation in noncompact manifolds. The result is new even in the Euclidean
space.
In the subcritical, parabolic case, we also prove the convergence of some global
solutions to nontrivial stationary solutions.
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