On the computation of l- groups and natural maps

2002 ◽  
Vol 72 (1) ◽  
pp. 297-308 ◽  
Author(s):  
Beatrice Ruini ◽  
Fulvia Spaggiari
Keyword(s):  
Natural Maps

Natural maps of extension functors and a theorem of R. G. Swan

1961 ◽  
Vol 57 (3) ◽  
pp. 489-502 ◽  
Author(s):  
P. J. Hilton ◽  
D. Rees
Keyword(s):  
Finite Group ◽  
Exact Sequence ◽  
Group Ring ◽  
Projective Module ◽  
Additive Group ◽  
Integral Group Ring ◽  
Integral Group ◽  
Natural Maps ◽  
Image Position ◽  
A Finite Group

The present paper has been inspired by a theorem of Swan(5). The theorem can be described as follows. Let G be a finite group and let Γ be its integral group ring. We shall denote by Z an infinite cyclic additive group considered as a left Γ-module by defining gm = m for all g in G and m in Z. By a Tate resolution of Z is meant an exact sequencewhere Xn is a projective module for − ∞ < n < + ∞, and.

A note on natural maps of higher extension functors

1963 ◽  
Vol 59 (2) ◽  
pp. 283-286 ◽  
Author(s):  
F. Oort
Keyword(s):  
Natural Maps ◽  
Image Position

Hilton and Rees have proved (cf. (1), Theorem 1·3) that every natural mapis induced by a map from A to B (or, Hom (A, B) → Next1,1 (A, B) is surjective). It follows that Ext1 (B, −) and Ext1 (A, −) are naturally isomorphic if and only if A and B are quasi-isomorphic (loc. cit., Theorem 2·6), i.e. if there exist projective objects P, Q and an isomorphism . One can ask whether these theorems remain true for higher extension functors.

Natural maps on the iterated jet prolongation of a fibred manifold

1991 ◽  
Vol 158 (1) ◽  
pp. 151-165 ◽  
Author(s):  
Ivan Kolář ◽  
Marco Modugno
Keyword(s):  
Natural Maps ◽  
Fibred Manifold ◽  
Jet Prolongation

Natural maps depending on reductions of frame bundles

2011 ◽  
Vol 102 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Ivan Kolář
Keyword(s):  
Natural Maps

An Archaeological Survey of the Tehuacan Valley, Mexico: A Test of Color Infrared Photography

1972 ◽  
Vol 37 (4) ◽  
pp. 520-527 ◽  
Author(s):  
George J. Gumerman ◽  
James A. Neely
Keyword(s):  
Archaeological Survey ◽  
Tehuacán Valley ◽  
Infrared Photography ◽  
Environmental Situation ◽  
Natural Maps ◽  
Tehuacan Valley ◽  
Cultural Feature ◽  
Using Data ◽  
Cultural Features

AbstractUsing data collected by NASA in the Tehuacan Valley, Mexico, tests were undertaken to determine the effectiveness of aerial color infrared film for archaeological reconnaissance. The study area was chosen primarily because MacNeish's Tehuacan Archaeological-Botanical Project (1960-1964) provided a convenient check of site visibility on the photographs, and because microenvironmental zones have been delineated in the valley allowing visibility of sites in different microenvironments to be determined. Our tests indicate that the type of cultural feature or its age are not as important as the environmental situation in distinguishing the site. The greatest archaeological value, however, of color infrared photography is in the delineation of microenvironmental zones and the construction of natural maps rather than the identification of cultural features.

scholarly journals The topological structure of 𝒟–classes

1969 ◽  
Vol 1 (3) ◽  
pp. 289-295
Author(s):  
A.R. Stralka
Keyword(s):  
Topological Semigroup ◽  
Topological Structure ◽  
Cartesian Product ◽  
Fibre Space ◽  
Natural Maps ◽  
Compact Topological Semigroup

Let S be a compact, topological semigroup with identity. Suppose D, L and R are the D, L and R classes of some x ∈ S. Let (L, α., L/H), (R, β, R/H), (D, γ, D/H) and (D, δ, D/R) by the fibre spaces gotten where α, β γ an δ are the natural maps. It is shown that (D, γ, D/H) has topologically the same structure as the fibre space associated with (L, α, L/H) by R. Also if (L, α, L/H) is locally trivial (locally a cartesian product) then so is (D, δ, D/R) and if both (L, α, L/H) and (R, β, R/H) are locally trivial then so is (D, γ, D/H).

scholarly journals Natural maps of extension functors

1963 ◽  
Vol 66 ◽  
pp. 559-566 ◽  
Author(s):  
F. Oort
Keyword(s):  
Natural Maps

scholarly journals On number fields with given ramification

2007 ◽  
Vol 143 (6) ◽  
pp. 1359-1373 ◽  
Author(s):  
Gaëtan Chenevier
Keyword(s):  
Prime Number ◽  
Number Field ◽  
Number Fields ◽  
Algebraic Extension ◽  
Natural Maps ◽  
Finite Set ◽  
Totally Real

AbstractLet E be a CM number field and let S be a finite set of primes of E containing the primes dividing a given prime number l and another prime u split above the maximal totally real subfield of E. If ES denotes a maximal algebraic extension of E which is unramified outside S, we show that the natural maps $\mathrm {Gal}(\overline {E_u}/E_u) \longrightarrow \mathrm {Gal}(E_S/E)$ are injective. We discuss generalizations of this result.

scholarly journals When certain natural maps are equivalences

1972 ◽  
Vol 42 (1) ◽  
pp. 69-75
Author(s):  
Richard Holzsager
Keyword(s):  
Natural Maps
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