  We investigate the Seiberg-Witten monopole equations on noncommutative(N.C.)
R^4 at the large N.C. parameter limit, in terms of the equivariant cohomology.
In other words, N}=2 supersymmetric U(1) gauge theories with hypermultiplet on
N.C. R}^4 are studied. It is known that after topological twisting partition
functions of N}>1 supersymmetric theories on N.C. R^2D are invariant under
N.C.parameter shift, then the partition functions can be calculated by its
dimensional reduction. At the large N.C. parameter limit, the Seiberg-Witten
monopole equations are reduced to ADHM equations with the Dirac equation
reduced to 0 dimension. The equations are equivalent to the dimensional
reduction of non-Abelian U(N) Seiberg-Witten monopole equations in N -> \infty.
The solutions of the equations are also interpreted as a configuration of brane
anti-brane system. The theory has global symmetries under torus actions
originated in space rotations and gauge symmetries. We investigate the
Seiberg-Witten monopole equations reduced to 0 dimension and the fixed point
equations of the torus actions. We show that the Dirac equation reduced to 0
dimension is trivial when the fixed point equations and the ADHM equations are
satisfied. For finite N, it is known that the fixed points of the ADHM data are
isolated and are classified by the Young diagrams. We give a new proof of this
statement by solving the ADHM equations and the fixed point equations
concretely and by giving graphical interpretations of the field components and
these equations.
