@article{3063148,
    title = "Generalized harmonic functions on trees: Universality and frequent universality",
    author = "Biehler, N. and Nestoridi, E. and Nestoridis, V.",
    journal = "Australian Journal of Mathematical Analysis and Applications",
    year = "2021",
    volume = "503",
    number = "1",
    publisher = "Academic Press Inc.",
    issn = "1449-5910",
    doi = "10.1016/j.jmaa.2021.125277",
    abstract = "Recently, harmonic functions and frequently universal harmonic functions on a tree T have been studied, taking values on a separable Fréchet space E over the field C or R. In the present paper, we allow the functions to take values in a vector space E over a rather general field F. The metric of the separable topological vector space E is translation invariant and instead of harmonic functions we can also study more general functions defined by linear combinations with coefficients in F. We don't assume that E is complete and therefore we present an argument avoiding Baire's theorem. © 2021 Elsevier Inc."
}