A fibration-like structure called a hyperpencil is defined on a smooth, closed 2n-manifold X, generalizing a linear system of curves on an algebraic variety. A deformation class of hyperpencils is shown to determine an isotopy class of symplectic structures on X. This provides an inverse to Donaldson's program for constructing linear systems on symplectic manifolds. In dimensions ≤ 6, work of Donaldson and Auroux provides hyperpencils on any symplectic manifold, and the author conjectures that this extends to arbitrary dimensions. In dimensions where this holds, the set of deformation classes of hyperpencils canonically maps onto the set of isotopy classes of rational symplectic forms up to positive scale, topologically determining a dense subset of all symplectic forms up to an equivalence relation on hyperpencils. In particular, the existence of a hyperpencil topologically characterizes those manifolds in dimensions ≤ 6 (and perhaps in general) that admit symplectic structures.

The purpose of this note is to present a construction of an infinite family of symplectic tori T^p,q representing an arbitrary multiple q[F] of the homology class [F] of the fiber of an elliptic surface E(n), for n ≥ 3, such that, for i ≠ j, there is no orientation-preserving diffeomorphism between (E(n), T^(i,q)) and (E(n), T^(i,q)). In particular, these tori are mutually nonisotopic. This complements previous results of Fintushel and Stern in [FS2], showing in particular the existence of such phenomenon for a primitive class.

This paper is the last in a series of three papers which investigate pseudoholomorphic strips in the symplectisation of a three dimensional closed contact manifold with a mixed boundary condition. We will prove a compactness and an intersection result, and we will investigate the embedding properties of such pseudoholomorphic curves.

In this note we prove a simple relation between the mean curvature form, symplectic area, and the Maslov class of a Lagrangian immersion in a Kähler-Einstein manifold. An immediate consequence is that in Kähler-Einstein manifolds with positive scalar curvature, minimal Lagrangian immersions are monotone.

Consider a Hamiltonian action of a compact Lie group on a symplectic manifold which has the strong Lefschetz property. We establish an equivariant version of the Merkulov- Guillemin dδ-lemma and an improved version of the Kirwan- Ginzburg equivariant formality theorem, which says that every cohomology class has a canonical equivariant extension.