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1.
We study groups whose cohomology functors commute with filtered colimits in high dimensions. We relate this condition to the existence of projective resolutions which exhibit some finiteness properties in high dimensions, and to the existence of Eilenberg–Mac Lane spaces with finitely many n-cells for all sufficiently large n. To that end, we determine the structure of completely finitary Gorenstein projective modules over group rings. The methods are inspired by representation theory and make use of the stable module category, in which morphisms are defined through complete cohomology. In order to carry out these methods, we need to restrict ourselves to certain classes of hierarchically decomposable groups. 相似文献
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5.
Olympia Talelli 《代数通讯》2013,41(3):1167-1172
Here we show that a countable group G has periodic cohomology of period q after some steps with the periodicity isomorphisms induced by cup product with an element in H q (G, ?) if and only if G has periodic homology of period q after some steps with the periodicity isomorphisms induced by cap product with an element in H q (G, ?). In [2] Asadollahi, Hajizamani, and Salarian showed that, if a group G is such that every flat ?G-module has finite projective dimension, then G has periodic cohomology of period q after some steps with the periodicity isomorphisms induced by cup product with an element in H q (G, ?) if and only if G has periodic homology of period q after some steps with the periodicity isomorphisms induced by cap product with an element in H q (G, C), where C is the cotorsion envelope of the trivial ?G-module ?. 相似文献
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Olympia Talelli 《Archiv der Mathematik》2007,89(1):24-32
We define a group G to be of type Φ if it has the property that for every
-module G, proj.
G < ∞ iff proj.
H G < ∞ for every finite subgroup H of G. We conjecture that the type Φ is an algebraic characterization of those groups G which admit a finite dimensional model for
, the classifying space for the family of the finite subgroups of G. We also conjecture that the type Φ is equivalent to spli being finite, where spli
is the supremum of the projective lengths of the injective
-modules. Here we prove certain parts of these conjectures.
The project is cofounded by the European Social Fund and National Resources–EPEAK II–Pythagoras.
Received: 21 June 2006 相似文献
8.
Olympia Talelli 《代数通讯》2013,41(11):1343-1360
9.
Olympia E. Demesouka Konstantinos P. Anagnostopoulos 《European Journal of Operational Research》2019,272(2):574-586
Multicriteria spatial decision support systems (MC-SDSS) have emerged as an integration of geographical information systems (GIS) and multiple criteria decision aid (MCDA) methods for incorporating conflicting objectives and decision makers’ preferences into spatial decision models. In this paper, we present spatial UTASTAR (S-UTASTAR), a raster-based MC-SDSS for land-use suitability analysis. The multicriteria component of the system is based on the UTA-type disaggregation-aggregation approach. S-UTASTAR is applied in a raster-based case study concerning land-use suitability analysis to identify appropriate municipal solid waste landfill (MSW) sites in Northeast Greece. Moreover, robustness analysis tools are implemented to guarantee robust decision support results. More specifically, during the aggregation phase, the Stochastic Multiobjective Acceptability Analysis (SMAA) is used to indicate the frequency at which a site achieves the best ranking positions within a large set of alternative landfill sites. 相似文献
10.
In [1, 3] it was shown: Theorem A. If G is the fundamental group of a finite graph of λ-dimensional duality groups with |G
o(e) : G
e
| < ∞ and |G
τ(e) : G
e
| < ∞ for every edge e of the corresponding G-tree, then G is an (λ + 1)-dimensional duality group.
Here we use the methods of Brown and Geoghegan in [3] to obtain examples of duality groups under weaker conditions than those
of Theorem A.
Received: 5 June 2007 相似文献