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In algebraic topology, a branch of mathematics, a spectrum is an object representing a generalized cohomology theory. There are several different constructions of categories of spectra, any of which gives a context for the same stable homotopy theory.

The definition of a spectrum

There are many variations of the definition: in general, a "spectrum" is any sequence $X_{n}$ of pointed topological spaces or pointed simplicial sets together with the structure maps $S^{1} \land X_{n} \to X_{n + 1}$ .

The treatment here is due to Adams (1974): a spectrum (a CW-spectrum) is a sequence $E : = {E_{n}}_{n \in ℕ}$ of CW-complexes together with inclusions $Σ E_{n} \to E_{n + 1}$ of the suspension $Σ E_{n}$ as a subcomplex of $E_{n + 1}$ .

For other definitions, see symmetric spectrum and simplicial spectrum.

Examples

Consider singular cohomology $H^{n} (X; A)$ with coefficients in an abelian group A. By Brown representability $H^{n} (X; A)$ is the set of homotopy classes of maps from X to K(A,n), the Eilenberg-MacLane space with homotopy concentrated in degree n. Then the corresponding spectrum HA has n'th space K(A,n); it is called the Eilenberg–MacLane spectrum.

As a second important example, consider topological K-theory. At least for X compact, $K^{0} (X)$ is defined to be the Grothendieck group of the monoid of complex vector bundles on X. Also, $K^{1} (X)$ is the group corresponding to vector bundles on the suspension of X. Topological K-theory is a generalized cohomology theory, so it gives a spectrum. The zero'th space is $ℤ \times B U$ while the first space is $U$ . Here $U$ is the infinite unitary group and $B U$ is its classifying space. By Bott periodicity we get $K^{2 n} (X) ≅ K^{0} (X)$ and $K^{2 n + 1} (X) ≅ K^{1} (X)$ for all n, so all the spaces in the topological K-theory spectrum are given by either $ℤ \times B U$ or $U$ . There is a corresponding construction using real vector bundles instead of complex vector bundles, which gives an 8-periodic spectrum.

For many more examples, see the list of cohomology theories.

A spectrum may be constructed out of a space. The suspension spectrum of a space X is a spectrum $X_{n} = S^{n} \land X$ (the structure maps are the identity.) For example, the suspension spectrum of a 0-sphere is called the sphere spectrum and is denoted by $𝕊$ .
An Ω-spectrum is a spectrum such that the adjoint of the structure map; that is, $X_{n} \to Ω X_{n + 1}$ is a weak equivalence. The K-theory spectrum of a ring is an example of an Ω-spectrum.
A ring spectrum is a spectrum X such that the diagrams that describe ring axioms in terms of smash products commute "up to homotopy" ( $S^{0} \to X$ corresponds to the identity.) For example, the spectrum of a topological K-theory is a ring spectrum. A module spectrum may be defined analogously.

Invariants

The homotopy group of a spectrum $X_{n}$ is given by $π_{k} (X) = {colim}_{n} π_{n + k} (X_{n})$ . Thus, for example, $π_{k} (𝕊)$ , $𝕊$ sphere spectrum, is the k-th stable homotopy group of a sphere. A spectrum is said to be connective if its $π_{k}$ are zero for negative k.

Functions, maps, and homotopies of spectra

There are three natural categories whose objects are spectra, whose morphisms are the functions, or maps, or homotopy classes defined below.

A function between two spectra E and F is a sequence of maps from E_n to F_n that commute with the maps ΣE_n → E_n+1 and ΣF_n → F_n+1.

Given a spectrum $E_{n}$ , a subspectrum $F_{n}$ is a sequence of subcomplexes that is also a spectrum. As each i-cell in $E_{j}$ suspends to an (i + 1)-cell in $E_{j + 1}$ , a cofinal subspectrum is a subspectrum for which each cell of the parent spectrum is eventually contained in the subspectrum after a finite number of suspensions. Spectra can then be turned into a category by defining a map of spectra $f : E \to F$ to be a function from a cofinal subspectrum $G$ of $E$ to $F$ , where two such functions represent the same map if they coincide on some cofinal subspectrum. Intuitively such a map of spectra does not need to be everywhere defined, just eventually become defined, and two maps that coincide on a cofinal subspectrum are said to be equivalent. This gives the category of spectra (and maps), which is a major tool. There is a natural embedding of the category of pointed CW complexes into this category: it takes $Y$ to the suspension spectrum in which the nth complex is $Σ^{n} Y$ .

The smash product of a spectrum $E$ and a pointed complex $X$ is a spectrum given by $(E \land X)_{n} = E_{n} \land X$ (associativity of the smash product yields immediately that this is indeed a spectrum). A homotopy of maps between spectra corresponds to a map $(E \land I^{+}) \to F$ , where $I^{+}$ is the disjoint union $[0, 1] ⊔ {*}$ with * taken to be the basepoint.

The stable homotopy category, or homotopy category of (CW) spectra is defined to be the category whose objects are spectra and whose morphisms are homotopy classes of maps between spectra. Many other definitions of spectrum, some appearing very different, lead to equivalent stable homotopy categories.

Finally, we can define the suspension of a spectrum by $(Σ E)_{n} = E_{n + 1}$ . This translation suspension is invertible, as we can desuspend too, by setting $(Σ^{- 1} E)_{n} = E_{n - 1}$ .

The triangulated homotopy category of spectra

The stable homotopy category is additive: maps can be added by using a variant of the track addition used to define homotopy groups. Thus homotopy classes from one spectrum to another form an abelian group. Furthermore the stable homotopy category is triangulated (Vogt (1970)), the shift being given by suspension and the distinguished triangles by the mapping cone sequences of spectra

X \to Y \to Y \cup C X \to (Y \cup C X) \cup C Y ≅ Σ X

.

Smash products of spectra

The smash product of spectra extends the smash product of CW complexes. It makes the stable homotopy category into a monoidal category; in other words it behaves like the tensor product of abelian groups. A major problem with the smash product is that obvious ways of defining it make it associative and commutative only up to homotopy. Some more recent definitions of spectra, such as symmetric spectra, eliminate this problem, and give a symmetric monoidal structure at the level of maps, before passing to homotopy classes.

The smash product is compatible with the triangulated category structure. In particular the smash product of a distinguished triangle with a spectrum is a distinguished triangle.

Generalized homology and cohomology of spectra

We can define the (stable) homotopy groups of a spectrum to be those given by

π_{n} E = [Σ^{n} S, E]

,

where $S$ is the spectrum of spheres and $[X, Y]$ is the set of homotopy classes of maps from $X$ to $Y$ . We define the generalized homology theory of a spectrum E by

E_{n} X = π_{n} (E \land X) = [Σ^{n} S, E \land X]

and define its generalized cohomology theory by

E^{n} X = [Σ^{- n} X, E] .

Here $X$ can be a spectrum or a (by using its suspension spectrum) a space.

History

A version of the concept of a spectrum was introduced in the 1958 doctoral dissertation of Elon Lages Lima. His advisor Edwin Spanier wrote further on the subject in 1959. Spectra were adopted by Michael Atiyah and George W. Whitehead in their work on generalized homology theories in the early 1960s. The 1964 doctoral thesis of J. Michael Boardman gave a workable definition of a category of spectra and of maps (not just homotopy classes) between them, as useful in stable homotopy theory as the category of CW complexes is in the unstable case. (This is essentially the category described above, and it is still used for many purposes: for other accounts, see Adams (1974) or Vogt (1970).) Important further theoretical advances have however been made since 1990, improving vastly the formal properties of spectra. Consequently, much recent literature uses modified definitions of spectrum: see Mandell et al. (2001) for a unified treatment of these new approaches.

References

Adams, J. F.(1974), "Stable homotopy and generalised homology". University of Chicago Press
Atiyah, M. F.(1961), "Bordism and cobordism", Proc. Camb. Phil. Soc. 57: 200–208

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Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

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15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

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Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

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Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010

Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

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Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010

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+In [[algebraic topology]], a branch of [[mathematics]], a '''spectrum''' is an object representing a [[Cohomology#Generalized cohomology theories|generalized cohomology theory]]. There are several different constructions of categories of spectra, any of which gives a context for the same [[stable homotopy theory]].
+==The definition of a spectrum==
+There are many variations of the definition: in general, a "spectrum" is any sequence <math>X_n</math> of pointed topological spaces or pointed simplicial sets together with the structure maps <math>S^1 \wedge X_n \to X_{n+1}</math>.
+The treatment here is due to Adams (1974): a spectrum (a CW-spectrum) is a sequence <math>E:= \{E_n\}_{n\in \mathbb{N}} </math> of [[CW-complex]]es   together with inclusions <math> \Sigma E_n \to E_{n+1}  </math> of the [[suspension (topology)|suspension]] <math> \Sigma E_n  </math> as a subcomplex of <math>  E_{n+1}  </math>.
+For other definitions, see [[symmetric spectrum]] and [[simplicial spectrum]].
+== Examples ==
+Consider [[singular cohomology]] <math> H^n(X;A) </math> with coefficients in an [[abelian group]] A. By [[Brown representability]] <math> H^n(X;A) </math> is the set of homotopy classes of maps from X to K(A,n), the [[Eilenberg-MacLane space]] with homotopy concentrated in degree n. Then the corresponding spectrum HA has n'th space K(A,n); it is called the ''Eilenberg–MacLane spectrum''.
+As a second important example, consider [[topological K-theory]]. At least for X compact, <math> K^0(X) </math> is defined to be the [[Grothendieck group]] of the [[monoid]] of complex [[vector bundles]] on X. Also, <math> K^1(X) </math> is the group corresponding to vector bundles on the suspension of X. Topological K-theory is a generalized cohomology theory, so it gives a spectrum. The zero'th space is <math> \mathbb{Z} \times BU </math> while the first space is <math>U</math>. Here <math>U</math> is the infinite [[unitary group]] and <math>BU</math> is its [[classifying space]]. By [[Bott periodicity]] we get <math> K^{2n}(X) \cong K^0(X) </math> and <math> K^{2n+1}(X) \cong K^1(X) </math> for all ''n'', so all the spaces in the topological K-theory spectrum are given by either <math> \mathbb{Z} \times BU </math> or <math>U</math>. There is a corresponding construction using real vector bundles instead of complex vector bundles, which gives an 8-periodic spectrum.
+For many more examples, see the [[list of cohomology theories]].
+*A spectrum may be constructed out of a space. The '''suspension spectrum''' of a space ''X'' is a spectrum <math>X_n = S^n \wedge X</math> (the structure maps are the identity.) For example, the suspension spectrum of a [[0-sphere]] is called the [[sphere spectrum]] and is denoted by <math>\mathbb{S}</math>.
+*An '''Ω-spectrum''' is a spectrum such that the adjoint of the structure map; that is, <math>X_n \to \Omega X_{n+1}</math> is a weak equivalence. The [[K-theory spectrum]] of a ring is an example of an Ω-spectrum.
+*A [[ring spectrum]] is a spectrum ''X'' such that the diagrams that describe [[ring axioms]] in terms of smash products commute "up to homotopy" (<math>S^0 \to X</math> corresponds to the identity.) For example, the spectrum of a topological ''K''-theory is a ring spectrum. A '''module spectrum''' may be defined analogously.
+== Invariants ==
+*The homotopy group of a spectrum <math>X_n</math> is given by <math>\pi_k(X) = \operatorname{colim}_{n} \pi_{n+k}(X_n)</math>. Thus, for example, <math>\pi_k(\mathbb{S})</math>, <math>\mathbb{S}</math> sphere spectrum, is the ''k''-th [[stable homotopy group]] of a sphere. A spectrum is said to be [[Connective spectrum|connective]] if its <math>\pi_k</math> are zero for negative ''k''.
+==Functions, maps, and homotopies of spectra==
+There are three natural categories whose objects are spectra, whose morphisms are the functions, or maps, or homotopy classes defined below.
+A '''function''' between two spectra ''E'' and ''F'' is a sequence of maps from ''E''<sub>''n''</sub> to ''F''<sub>''n''</sub> that commute with the
+maps Σ''E''<sub>''n''</sub>&nbsp;→&nbsp;''E''<sub>''n''+1</sub> and Σ''F''<sub>''n''</sub>&nbsp;→&nbsp;''F''<sub>''n''+1</sub>.
+Given a spectrum <math>E_n</math>, a subspectrum <math>F_n</math> is a sequence of subcomplexes that is also a spectrum.  As each ''i''-cell in <math>E_j</math> suspends to an (''i''&nbsp;+&nbsp;1)-cell in <math>E_{j+1}</math>, a cofinal subspectrum is a subspectrum for which each cell of the parent spectrum is eventually contained in the subspectrum after a finite number of suspensions.  Spectra can then be turned into a category by defining a '''map''' of spectra <math>f: E \to F</math> to be a function from a cofinal subspectrum <math>G</math> of <math>E</math>  to <math>F</math>, where two such functions represent the same map if they coincide on some cofinal subspectrum.  Intuitively such a map of spectra does not need to be everywhere defined, just ''eventually'' become defined, and two maps that coincide on a cofinal subspectrum are said to be equivalent.
+This gives the '''category of spectra''' (and maps), which is a major tool. There is a natural embedding of the category of pointed CW complexes into this category: it takes  <math> Y </math> to the ''suspension spectrum'' in which the ''n''th complex is <math> \Sigma^n Y </math>.
+The [[smash product]] of a spectrum <math>E</math> and a pointed complex <math>X</math> is a spectrum given by <math>(E \wedge X)_n = E_n \wedge X</math> (associativity of the smash product yields immediately that this is indeed a spectrum).  A homotopy of maps between spectra corresponds to a map <math>(E \wedge I^+) \to F</math>, where <math>I^+</math> is the disjoint union <math>[0, 1] \sqcup \{*\}</math> with * taken to be the basepoint.
+The '''stable homotopy category''', or '''homotopy category of (CW) spectra''' is defined to be the category whose objects are spectra and whose morphisms are homotopy classes of maps between spectra.   Many other definitions of spectrum, some appearing very different, lead to equivalent stable homotopy categories.
+Finally, we can define the suspension of a spectrum by <math>(\Sigma E)_n = E_{n+1}</math>. This '''translation suspension''' is invertible, as we can desuspend too, by setting <math>(\Sigma^{-1}E)_n = E_{n-1}</math>.
+==The triangulated homotopy category of spectra==
+The stable homotopy category is additive: maps can be added by using a variant of the track addition used to define homotopy groups. Thus homotopy classes from one spectrum to another form an abelian group.  Furthermore the stable homotopy category is [[triangulated category| triangulated]] (Vogt (1970)), the shift being given by suspension and the distinguished triangles by the [[mapping cone]] sequences of spectra
+:<math>X\rightarrow Y\rightarrow Y\cup CX \rightarrow (Y\cup CX)\cup CY \cong \Sigma X</math>.
+==Smash products of spectra==
+The [[smash product]] of spectra extends the smash product of CW complexes. It makes the stable homotopy category into a [[monoidal category]]; in other words it behaves like the tensor product of abelian groups. A major problem with the smash product is that obvious ways of defining it make it associative and commutative only up to homotopy. Some more recent definitions of spectra, such as [[symmetric spectrum|symmetric spectra]], eliminate this problem, and give a symmetric monoidal structure at the level of maps, before passing to homotopy classes.
+The smash product is compatible with the triangulated category structure. In particular the smash product of a distinguished triangle with a spectrum is a distinguished triangle.
+==Generalized homology and cohomology of spectra==
+We can define the [[stable homotopy group|(stable) homotopy groups]] of a spectrum to be those given by
+:<math>\displaystyle \pi_n E = [\Sigma^n S, E]</math>,
+where <math>S</math> is the [[sphere spectrum|spectrum of spheres]] and <math>[X, Y]</math> is the set of homotopy classes of maps from <math>X</math> to <math>Y</math>.
+We define the generalized homology theory of a spectrum ''E'' by
+:<math>E_n X = \pi_n (E \wedge X) = [\Sigma^n S, E \wedge X]</math>
+and define its generalized cohomology theory by
+:<math>\displaystyle E^n X = [\Sigma^{-n} X, E].</math>
+Here <math>X</math> can be a spectrum or a (by using its suspension spectrum) a space.
+==History==
+A version of the concept of a spectrum was introduced in the 1958 doctoral dissertation of Elon Lages Lima. His advisor [[Edwin Spanier]] wrote further on the subject in 1959. Spectra were adopted by [[Michael Atiyah]] and [[George W. Whitehead]] in their work on generalized homology theories in the early 1960s.  The 1964 doctoral thesis of [[Michael Boardman|J. Michael Boardman]] gave a workable definition of a category of spectra and of maps (not just homotopy classes) between them, as useful in stable homotopy theory as the category of [[CW complex]]es is in the unstable case.  (This is essentially the category described above, and it is still used for many purposes: for other accounts, see [[Frank Adams|Adams]] (1974) or [[Rainer Vogt|Vogt]] (1970).)    Important further theoretical advances have however been made since 1990, improving vastly the formal properties of spectra.  Consequently, much recent literature uses [[E-infinity ring spectrum|modified definitions of spectrum]]: see Mandell ''et al.'' (2001) for a unified treatment of these new approaches.
+== See also ==
+*[[Ring spectrum]]
+*[[Symmetric spectrum]]
+== References ==
+*  Adams, J. F.(1974), "Stable homotopy and generalised homology".  University of Chicago Press
+* [[Michael Atiyah|Atiyah, M. F.]](1961), "Bordism and cobordism", ''Proc. Camb. Phil. Soc.'' '''57''': 200–208
+*{{Citation | last1=Elmendorf | first1=A. D. | last2=Kříž | first2=I. | last3=Mandell | first3=M. A. | last4=May | first4=J. Peter | author4-link=J. Peter May | editor1-last=James. | editor1-first=I. M. | title=Handbook of algebraic topology | url=http://www.math.uchicago.edu/~may/PAPERS/Newfirst.pdf | publisher=North-Holland | location=Amsterdam | isbn=978-0-444-81779-2  | doi=10.1016/B978-044481779-2/50007-9 | mr=1361891 | year=1995 | chapter=Modern foundations for stable homotopy theory | pages=213–253}}
+*{{Citation | last1=Lima | first1=Elon L. | title=The Spanier–Whitehead duality in new homotopy categories | mr=0116332 | year=1959 | journal=Summa Brasil. Math. | volume=4 | pages=91–148}}
+* {{citation
+    | first = Elon |last= Lages Lima
+    | year = 1960
+    | title = Stable Postnikov invariants and their duals
+    | journal =  Summa Brasil. Math.
+    | volume = 4
+    | pages = 193–251
+}}
+* {{citation
+    | first = M. A.|last= Mandell|first2=J. P.|last2= May|first3= S. |last3=Schwede |first4=B. |last4=Shipley
+    | year = 2001
+    | title = Model categories of diagram spectra
+    | journal =  Proc. London Math. Soc. (3)
+    | volume = 82
+    | pages = 441–512
+    |doi=10.1112/S0024611501012692
+    | issue = 2
+}}
+*{{Citation | last1=Vogt | first1=Rainer | title=Boardman's stable homotopy category | url=http://books.google.com/books?id=xlvvAAAAMAAJ | publisher=Matematisk Institut, Aarhus Universitet, Aarhus | series=Lecture Notes Series, No. 21 | mr=0275431 | year=1970}}
+* {{citation
+    | first = George W. |last = Whitehead
+    | year = 1962
+    | title = Generalized homology theories
+    | journal =  Trans. Amer. Math. Soc.
+    | volume = 102
+    | pages = 227–283
+    | doi = 10.1090/S0002-9947-1962-0137117-6
+    | issue = 2
+}}
+{{DEFAULTSORT:Spectrum (Homotopy Theory)}}
+[[Category:Homotopy theory]]

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Revision as of 01:34, 30 January 2014

Contents

The definition of a spectrum

Examples

Invariants

Functions, maps, and homotopies of spectra

The triangulated homotopy category of spectra

Smash products of spectra

Generalized homology and cohomology of spectra

History

See also

References

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Shift-share analysis: Difference between revisions

Revision as of 01:34, 30 January 2014

The definition of a spectrum

Examples

Invariants

Functions, maps, and homotopies of spectra

The triangulated homotopy category of spectra

Smash products of spectra

Generalized homology and cohomology of spectra

History

See also

References

Navigation menu

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