Nadim, AJ;
(2015)
A Periodic Monogenic Resolution.
Doctoral thesis , UCL(University College London).

## Abstract

In this thesis we examine the R(2) − D(2) problem for CW complexes with fundamental group isomorphic to the very non-abelian general affine group J = GA(1, F5) of order 20. In particular, since J is finite of cohomological period 8, it admits a periodic free resolution of finitely generated modules. We devote our efforts towards showing the existence of a diagonal free resolution of Z over Λ = Z[J] of period 8 via a neat decomposition of the syzygies Ωn(Z) (classes of modules stably isomorphic to certain kernels), which occur in a decomposed form in the constituent infinite monogenic resolutions. A traditional strategy for constructing a diagonal resolution would entail considering extensions of all possible sub-modules after extensive trial and error techniques. However, we side step this method by considering a more intellectual line, namely the kernels K(i) of the generators �(i) : Λ → θi of the row submodules θi ⊂ T4(Z, 5). We describe these kernels as distinct extensions of indecomposable modules and prove that each K(i) is in fact congruent to a quotient module of Λ. Moreover, we also examine the monogenicity of certain K(i) and we show how they relate to the Ωn(Z) . A diagonal resolution would significantly simplify group cohomology calculations Hn Λ(J; Z) ∼= Extn Λ (Z, Z) with coefficients in Z. Moreover, detailed knowledge of the free resolution is an essential step towards solving the R(2)− D(2)-problem positively for J. The D(2)-problem asks if a three-dimensional CW complex is homotopy equivalent to a two-dimensional CW complex provided H3(X, ˜ Z) = H3(X; B) = 0 for all coefficient systems B. Johnson proved that this problem is equivalent to a purely algebraic problem he called the R(2)-problem.

Type: | Thesis (Doctoral) |
---|---|

Title: | A Periodic Monogenic Resolution |

Language: | English |

Keywords: | Diagonal, Periodic, Monogenic, Free Resolution, R(2)-D(2) Problem, Non-abelian group of order 20 |

UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Mathematics |

URI: | https://discovery.ucl.ac.uk/id/eprint/1470758 |

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