Positive solutions of systems of semilinear elliptic equations: the pendulum method
Joseph Ryan Glover · Transactions of the American Mathematical Society · 1987
Conditions are formulated which guarantee the existence of positive solutions for systems of the form \[ − Δ u 1 + f 1 ( u 1 , … , u n ) = μ 1 , − Δ u 2 + f 2 ( u 1 , … , u n ) = μ 2 , ⋮ ⋮ ⋮ ⋮ − Δ u n + f n ( u 1 , … , u n