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Rewrote the answer in part to clarify terminology and to give a reference.
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Allan Edmonds
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No such actionThere is possible. Otherwise one would have a free action on a spherebit of lower dimension linkinga disconnect between the fixed point settitle and the actual question. But such an action would giveUsually a freesemifree action is one in which the only isotropy groups are the trivial group and the whole group. The actions with only finite isotropy groups, in the body of $G=\mathbf{Z}_p\times \mathbf{Z}_p$your question, are often called ``pseudofree'' actions. If a torus were to act pseudofreely on a sphere, violating then a subgroup of the known factform $G=\mathbf{Z}_{p}\times \mathbf{Z}_{p}$ for some prime $p$ would act freely on the sphere. It is well-known that such a finitethe latter group cannot act freely on a finite complex with the homology of a sphere. Such because such an action of $G$ can be shown by a splicing argument to provide a periodic resolution of $\mathbf{Z}$ as a trivial $\mathbf{Z}[G]$-module, violating the factwould imply that thisthe group does not havehas periodic cohomology, which (by the Kunneth formula)$G$ does not. See Bredon's book Introduction to Compact Transformation Groups, for example.

No such action is possible. Otherwise one would have a free action on a sphere of lower dimension linking the fixed point set. But such an action would give a free action of $G=\mathbf{Z}_p\times \mathbf{Z}_p$ on a sphere, violating the known fact that such a finite group cannot act freely on a finite complex with the homology of a sphere. Such an action of $G$ can be shown by a splicing argument to provide a periodic resolution of $\mathbf{Z}$ as a trivial $\mathbf{Z}[G]$-module, violating the fact that this group does not have periodic cohomology (by the Kunneth formula).

There is a bit of a disconnect between the title and the actual question. Usually a semifree action is one in which the only isotropy groups are the trivial group and the whole group. The actions with only finite isotropy groups, in the body of your question, are often called ``pseudofree'' actions. If a torus were to act pseudofreely on a sphere then a subgroup of the form $G=\mathbf{Z}_{p}\times \mathbf{Z}_{p}$ for some prime $p$ would act freely on the sphere. It is well-known that the latter group cannot act freely on a sphere because such an action would imply that the group has periodic cohomology, which $G$ does not. See Bredon's book Introduction to Compact Transformation Groups, for example.

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Allan Edmonds
  • 3.4k
  • 1
  • 28
  • 25

No such action is possible. Otherwise one would have a free action on a sphere of lower dimension linking the fixed point set. But such an action would give a free action of $G=\mathbf{Z}_p\times \mathbf{Z}_p$ on a sphere, violating the known fact that such a finite group cannot act freely on a finite complex with the homology of a sphere. Such an action of $G$ can be shown by a splicing argument to provide a periodic resolution of $\mathbf{Z}$ as a trivial $\mathbf{Z}[G]$-module, violating the fact that this group does not have periodic cohomology (by the Kunneth formula).