virtually

Almost but not quite.

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In essence or functionally, but not in fact, formally, or technically.

• virtually a member of the family

Of a subgroup of finite index.

• In this case W has a diagram with 2 vertices and one edge labelled ∞, and is therefore the infinite dihedral group. Thus W is virtually ℤ.
• In this paper, we are mainly concerned with homogeneity in the class of finitely generated virtually free groups, i.e. finitely generated groups with a free subgroup of finite index.

Of a covering space of finite degree.

• Another class of small manifolds consists of those that are not virtually Haken (a manifold is virtually Haken if it is finitely covered by a Haken manifold).
• We call a hyperplane Y in a VH-complex X virtually clean if there exists a finite-sheeted covering map p : X̂ → X and a connected component Y ⊆ p⁻¹Y such that the hyperplane Ŷ of X̂ is clean.

By computer or in cyberspace.