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We show how to construct broken, achiral Lefschetz fibrations on arbitrary smooth,
closed, oriented 4–manifolds. These are generalizations of Lefschetz fibrations over
the 2–sphere, where we allow Lefschetz singularities with the non-standard
orientation as well as circles of singularities corresponding to round 1–handles. We
can also arrange that a given surface of square 0 is a fiber. The construction is easier
and more explicit in the case of doubles of 4–manifolds without 3– and 4–handles,
such as the homotopy 4–spheres arising from nontrivial balanced presentations of the
trivial group.
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