Buildup of the resonance chain of the four Kepler-223 planets, without considering turbulence. The investigated parameter space is two dimensional: The surface density is varied, as is the initial separation of the planet pairs from the final resonance. The configurations in which the correct chain was built are indicated by green triangles, while those who failed to do so are shown as red crosses. The vales for ε are ordered such that ε₁ is the topmost value. Simulations whose symbol is encircled share their initial parameters with those considered for a consideration including disk turbulence (Sect. 3.2).