EN
For a given graph G and a sequence 𝓟₁, 𝓟₂,..., 𝓟ₙ of additive hereditary classes of graphs we define an acyclic (𝓟₁, 𝓟₂,...,Pₙ)-colouring of G as a partition (V₁, V₂,...,Vₙ) of the set V(G) of vertices which satisfies the following two conditions:
1. $G[V_i] ∈ 𝓟_i$ for i = 1,...,n,
2. for every pair i,j of distinct colours the subgraph induced in G by the set of edges uv such that $u ∈ V_i$ and $v ∈ V_j$ is acyclic.
A class R = 𝓟₁ ⊙ 𝓟₂ ⊙ ... ⊙ 𝓟ₙ is defined as the set of the graphs having an acyclic (𝓟₁, 𝓟₂,...,Pₙ)-colouring. If 𝓟 ⊆ R, then we say that R is an acyclic reducible bound for 𝓟. In this paper we present acyclic reducible bounds for the class of outerplanar graphs.