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stack - choose a jigsaw puzzle to solve

In mathematics a stack or 2-sheaf is, roughly speaking, a sheaf that takes values in categories rather than sets. Stacks are used to formalise some of the main constructions of descent theory, and to construct fine moduli stacks when fine moduli spaces do not exist. Descent theory is concerned with generalisations of situations where isomorphic, compatible geometrical objects (such as vector bundles on topological spaces) can be "glued together" within a restriction of the topological basis. In a more general set-up the restrictions are replaced with pullbacks; fibred categories then make a good framework to discuss the possibility of such gluing. The intuitive meaning of a stack is that it is a fibred category such that "all possible gluings work". The specification of gluings requires a definition of coverings with regard to which the gluings can be considered. It turns out that the general language for describing these coverings is that of a Grothendieck topology. Thus a stack is formally given as a fibred category over another base category, where the base has a Grothendieck topology and where the fibred category satisfies a few axioms that ensure existence and uniqueness of certain gluings with respect to the Grothendieck topology.
A beach. - A beach - I do not know where.
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A beach.

Added 3 months ago by Mila

45

Cliffs in Australia. - Cliffs Twelve Apostles in Australia.
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Cliffs in Australia.

Added 3 months ago by Zeta

48

Landscape - colorful jigsaw puzzle
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Landscape

Added 3 months ago by andi

62

BAJKOWY VIEW - Vacation, holidays, rest.
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BAJKOWY VIEW

Added 4 months ago by ada

29

BAJKOWY VIEW - Vacation, holidays, rest.
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BAJKOWY VIEW

Added 4 months ago by ada

69

Cliff in Normandy. - Sea cliff in Normandy.
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Cliff in Normandy.

Added year ago by Zeta

75

Coast in Scotland. - Coast in Scotland in the UK.
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Coast in Scotland.

Added year ago by Zeta

56

wonders of nature - sea ​​landscape, coast, ocean,
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wonders of nature

Added year ago by sandra

186

seaside landscape - sea, ocean, coast, cliffs
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seaside landscape

Added year ago by sandra

183

hole rock - sea, ocean, rocks, coast
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hole rock

Added year ago by sandra

101

Landscape - colorful jigsaw puzzle
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Landscape

Added year ago by andi

70

Lighthouse - colorful jigsaw puzzle
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Lighthouse

Added year ago by andi

243

BAJKOWY VIEW - Vacation, holidays, rest
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BAJKOWY VIEW

Added year ago by Ada

35 1

Landscape - colorful jigsaw puzzle
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Landscape

Added year ago by andi

142

landscape - colorful puzzle landscapes
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landscape

Added year ago by natalia

107

Landscape - colorful jigsaw puzzle
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Landscape

Added year ago by andi

200

Landscape - colorful jigsaw puzzle
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Landscape

Added year ago by andi

342

Cliffs of Moher - section of the cliff coast of the Atlantic Ocean in the western part of the Republic of Ireland (Cla
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Cliffs of Moher

Added year ago by natalia

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Azure Window - no longer existing rock bridge off the coast of the island of Gozo in the Republic of Malta
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Azure Window

Added year ago by Z&S

379

Azure Window - A non-existent rock bridge off the coast of the island of Gozo in the Republic of Malta.
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Azure Window

Added year ago by Z&S

77

IRELAND - IRELAND
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IRELAND

Added year ago by IRLANDIA

147

LIBANLIBAN - LIBANLIBANLIBANLIBAN
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LIBANLIBAN

Added year ago by LIBAN

113

Wyspy Kanaryjskie - widok na Ocean Spokojny
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Wyspy Kanaryjskie

Added over a year ago by Julia

225

Cypr po prostu - wakacje, morze, ciepło
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Cypr po prostu

Added over a year ago by polinne

567

Italia, Capri, Faraglioni - pojedyncze skaly w płd-zach cześci Capri
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Italia, Capri, Faraglioni

Added over a year ago by Irena

379

skała jak zwierzę - skała,słoń,woda,zieleń
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skała jak zwierzę

Added over a year ago by wieslawa

130

błękitne groty - Grecja,skały groty,woda,zieleń
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błękitne groty

Added over a year ago by wieslawa

332 1

Niecodzienne cuda natury - Niecodzienne cuda natury
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Niecodzienne cuda natury

Added over a year ago by Anita

90

Niecodzienne cuda natury - Niecodzienne cuda natury
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Niecodzienne cuda natury

Added over a year ago by Anita

169

Gargano Włochy - skały,drzewa,morze,kształty
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Gargano Włochy

Added over a year ago by wieslawa

180

Hiszpańskie wybrzeże... - Hiszpańskie wybrzeże a zachodzie słońca
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Hiszpańskie wybrzeże...

Added over a year ago by Anabell

594 1

niesamowity widok - co stworzyła woda z ziemi
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niesamowity widok

Added over a year ago by Basieńka

249

Hiszpańskie wybrzeże - Hiszpańskie wybrzeże
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Hiszpańskie wybrzeże

Added over a year ago by Anabell

770

Italia - Wyspa Capri - Italia - Capri. Przy południowo-wschodniej części wyspy spotkać można najbardziej charakterysty
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Italia - Wyspa Capri

Added over a year ago by Anabell

216