We show that the free-by-cyclic groups of the form F2⋊ Z act properly cocompactly on CAT(0) square complexes. We also show using generalized Baumslag-Solitar groups that all known groups defined bya 2-generator 1-relator presentation are either SQ-universal or arecyclic or isomorphic to a soluble Baumslag-Solitar group.
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