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The Integrated Density of States for Operators on Groups / Die Integrierte Zustandsdichte für Operatoren auf GruppenSchwarzenberger, Fabian 14 May 2014 (has links) (PDF)
This book is devoted to the study of operators on discrete structures. The operators are supposed to be self-adjoint and obey a certain translation invariance property. The discrete structures are given as Cayley graphs via finitely generated groups. Here, sofic groups and amenable groups are in the center of our considerations. Note that every finitely generated amenable group is sofic. We investigate the spectrum of a discrete self-adjoint operator by studying a sequence of finite dimensional analogues of these operators. In the setting of amenable groups we obtain these approximating operators by restricting the operator in question to finite subsets Qn , n ∈ N. These finite dimensional operators are self-adjoint and therefore admit a well-defined normalized eigenvalue counting function. The limit of the normalized eigenvalue counting functions when |Qn | → ∞ (if it exists) is called the integrated density of states (IDS). It is a distribution function of a probability measure encoding the distribution of the spectrum of the operator in question on the real axis.
We prove the existence of the IDS in various geometric settings and for different types of operators. The models we consider include deterministic as well as random situations. Depending on the specific setting, we prove existence of the IDS as a weak limit of distribution functions or even as a uniform limit. Moreover, in certain situations we are able to express the IDS via a semi-explicit formula using the trace of the spectral projection of the original operator. This is sometimes referred to as the validity of the Pastur-Shubin trace formula.
In the most general geometric setting we study, the operators are defined on Cayley graphs of sofic groups. Here we prove weak convergence of the eigenvalue counting functions and verify the validity of the Pastur-Shubin trace formula for random and non-random operators . These results apply to operators which not necessarily bounded or of finite hopping range. The methods are based on resolvent techniques. This theory is established without having an ergodic theorem for sofic groups at hand. Note that ergodic theory is the usual tool used in the proof of convergence results of this type.
Specifying to operators on amenable groups we are able to prove stronger results. In the discrete case, we show that the IDS exists uniformly for a certain class of finite hopping range operators. This is obtained by using a Banach space-valued ergodic theorem. We show that this applies to eigenvalue counting functions, which implies their convergence with respect to the Banach space norm, in this case the supremum norm. Thus, the heart of this theory is the verification of the Banach space-valued ergodic theorem. Proceeding in two steps we first prove this result for so-called ST-amenable groups. Then, using results from the theory of ε-quasi tilings, we prove a version of the Banach space-valued ergodic theorem which is valid for all amenable groups.
Focusing on random operators on amenable groups, we prove uniform existence of the IDS without the assumption that the operator needs to be of finite hopping range or bounded. Moreover, we verify the Pastur-Shubin trace formula. Here we present different techniques. First we show uniform convergence of the normalized eigenvalue counting functions adapting the technique of the Banach space-valued ergodic theorem from the deterministic setting. In a second approach we use weak convergence of the eigenvalue counting functions and additionally obtain control over the convergence at the jumps of the IDS. These ingredients are applied to verify uniform existence of the IDS. In both situations we employ results from the theory of large deviations, in order to deal with long-range interactions.
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Contributions to High–Dimensional Analysis under Kolmogorov ConditionPielaszkiewicz, Jolanta Maria January 2015 (has links)
This thesis is about high–dimensional problems considered under the so{called Kolmogorov condition. Hence, we consider research questions related to random matrices with p rows (corresponding to the parameters) and n columns (corresponding to the sample size), where p > n, assuming that the ratio <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%5Cfrac%7Bp%7D%7Bn%7D" /> converges when the number of parameters and the sample size increase. We focus on the eigenvalue distribution of the considered matrices, since it is a well–known information–carrying object. The spectral distribution with compact support is fully characterized by its moments, i.e., by the normalized expectation of the trace of powers of the matrices. Moreover, such an expectation can be seen as a free moment in the non–commutative space of random matrices of size p x p equipped with the functional <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20%5Cfrac%7B1%7D%7Bp%7DE%5BTr%5C%7B%5Ccdot%5C%7D%5D" />. Here, the connections with free probability theory arise. In the relation to that eld we investigate the closed form of the asymptotic spectral distribution for the sum of the quadratic forms. Moreover, we put a free cumulant–moment relation formula that is based on the summation over partitions of the number. This formula is an alternative to the free cumulant{moment relation given through non{crossing partitions ofthe set. Furthermore, we investigate the normalized <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20E%5B%5Cprod_%7Bi=1%7D%5Ek%20Tr%5C%7BW%5E%7Bm_i%7D%5C%7D%5D" /> and derive, using the dierentiation with respect to some symmetric matrix, a recursive formula for that expectation. That allows us to re–establish moments of the Marcenko–Pastur distribution, and hence the recursive relation for the Catalan numbers. In this thesis we also prove that the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20%5Cprod_%7Bi=1%7D%5Ek%20Tr%5C%7BW%5E%7Bm_i%7D%5C%7D" />, where <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20W%5Csim%5Cmathcal%7BW%7D_p(I_p,n)" />, is a consistent estimator of the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20E%5B%5Cprod_%7Bi=1%7D%5Ek%20Tr%5C%7BW%5E%7Bm_i%7D%5C%7D%5D" />. We consider <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20Y_t=%5Csqrt%7Bnp%7D%5Cbig(%5Cfrac%7B1%7D%7Bp%7DTr%5Cbig%5C%7B%5Cbig(%5Cfrac%7B1%7D%7Bn%7DW%5Cbig)%5Et%5Cbig%5C%7D-m%5E%7B(t)%7D_1%20(n,p)%5Cbig)," />, where <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20m%5E%7B(t)%7D_1%20(n,p)=E%5Cbig%5B%5Cfrac%7B1%7D%7Bp%7DTr%5Cbig%5C%7B%5Cbig(%5Cfrac%7B1%7D%7Bn%7DW%5Cbig)%5Et%5Cbig%5C%7D%5Cbig%5D" />, which is proven to be normally distributed. Moreover, we propose, based on these random variables, a test for the identity of the covariance matrix using a goodness{of{t approach. The test performs very well regarding the power of the test compared to some presented alternatives for both the high–dimensional data (p > n) and the multivariate data (p ≤ n).
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Contributions to High–Dimensional Analysis under Kolmogorov ConditionPielaszkiewicz, Jolanta Maria January 2015 (has links)
This thesis is about high–dimensional problems considered under the so{called Kolmogorov condition. Hence, we consider research questions related to random matrices with p rows (corresponding to the parameters) and n columns (corresponding to the sample size), where p > n, assuming that the ratio <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%5Cfrac%7Bp%7D%7Bn%7D" /> converges when the number of parameters and the sample size increase. We focus on the eigenvalue distribution of the considered matrices, since it is a well–known information–carrying object. The spectral distribution with compact support is fully characterized by its moments, i.e., by the normalized expectation of the trace of powers of the matrices. Moreover, such an expectation can be seen as a free moment in the non–commutative space of random matrices of size p x p equipped with the functional <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20%5Cfrac%7B1%7D%7Bp%7DE%5BTr%5C%7B%5Ccdot%5C%7D%5D" />. Here, the connections with free probability theory arise. In the relation to that eld we investigate the closed form of the asymptotic spectral distribution for the sum of the quadratic forms. Moreover, we put a free cumulant–moment relation formula that is based on the summation over partitions of the number. This formula is an alternative to the free cumulant{moment relation given through non{crossing partitions ofthe set. Furthermore, we investigate the normalized <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20E%5B%5Cprod_%7Bi=1%7D%5Ek%20Tr%5C%7BW%5E%7Bm_i%7D%5C%7D%5D" /> and derive, using the dierentiation with respect to some symmetric matrix, a recursive formula for that expectation. That allows us to re–establish moments of the Marcenko–Pastur distribution, and hence the recursive relation for the Catalan numbers. In this thesis we also prove that the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20%5Cprod_%7Bi=1%7D%5Ek%20Tr%5C%7BW%5E%7Bm_i%7D%5C%7D" />, where <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20W%5Csim%5Cmathcal%7BW%7D_p(I_p,n)" />, is a consistent estimator of the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20E%5B%5Cprod_%7Bi=1%7D%5Ek%20Tr%5C%7BW%5E%7Bm_i%7D%5C%7D%5D" />. We consider <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20Y_t=%5Csqrt%7Bnp%7D%5Cbig(%5Cfrac%7B1%7D%7Bp%7DTr%5Cbig%5C%7B%5Cbig(%5Cfrac%7B1%7D%7Bn%7DW%5Cbig)%5Et%5Cbig%5C%7D-m%5E%7B(t)%7D_1%20(n,p)%5Cbig)," />, where <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Csmall%20m%5E%7B(t)%7D_1%20(n,p)=E%5Cbig%5B%5Cfrac%7B1%7D%7Bp%7DTr%5Cbig%5C%7B%5Cbig(%5Cfrac%7B1%7D%7Bn%7DW%5Cbig)%5Et%5Cbig%5C%7D%5Cbig%5D" />, which is proven to be normally distributed. Moreover, we propose, based on these random variables, a test for the identity of the covariance matrix using a goodness{of{t approach. The test performs very well regarding the power of the test compared to some presented alternatives for both the high–dimensional data (p > n) and the multivariate data (p ≤ n).
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A Pastoral do Turismo e sua ambiguidade estruturalMoreno, Pedro Augusto Ceregatti 10 June 2016 (has links)
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Previous issue date: 2016-06-10 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Recognized by the World Tourism Organization (WTO) as a share of this market,
religious tourism provides significant revenue and traffic people, nationally and
internationally. Its expansion has come about in Brazil as recognition of their earning
potential. It’s results of transition from a phase in which the pilgrimages and festivals
did not happen spontaneously and management for the current state of business
structuring and training of its staff and services provided. Several factors are
intertwined in the development of this market in Brazil, and the government agencies
responsible for most of the investments in the sector. They promote infrastructure
improvements and incentive programs focused on events and religious attraction
poles, thereby providing enhancement of the hotel chain, transport connection,
agencies and tour operators. The Catholic Church is mobilizing to that particular field,
with its Pastur focused on the dissemination of shrines and religious appeal sites,
staff training and strategies that promote the sale of travel and tourism practices
packages Dioceses and parishes with potential attraction. This work exposes the one
hand, economically enterprising character of the church and on the other, the
ambiguity of the Pastur, as the pastoral intended for non-profit activities. Here is the
facet of Brazilian Catholicism to which this research is back. / Reconhecido pela Organização Mundial do Turismo (OMT) como uma parcela desse
mercado, o turismo religioso propicia significativo faturamento e trânsito de pessoas,
nacional e internacionalmente. Sua expansão vem se dando no Brasil conforme o
reconhecimento de seu potencial lucrativo. Decorre da transição de uma fase em
que as peregrinações e romarias não tinham gerenciamento e aconteciam
espontaneamente para o momento atual de estruturação e capacitação empresarial
de seus agentes e serviços prestados. Vários fatores estão interligados no
desenvolvimento desse mercado no Brasil, sendo os órgãos públicos responsáveis
por grande parte dos investimentos no setor. Eles promovem melhorias de
infraestrutura e programas de incentivo com foco em eventos e polos de atração
religiosa, propiciando assim aprimoramento da rede hoteleira, conexão de
transportes, agências e operadoras de viagens. A Igreja Católica vem se
mobilizando a fim de nesse campo específico, com sua Pastoral do Turismo (Pastur)
voltada para a divulgação de santuários e locais de apelo religioso, capacitação de
pessoal e estratégias de ação que fomentem a venda de pacotes de viagens e
práticas turísticas nas dioceses e paróquias com potencial de atração. Esse trabalho
expõe, de um lado, o caráter economicamente empreendedor da igreja e, de outro, a
ambiguidade da Pastur, dado que as pastorais, sobretudo as sociais como ela, se
destinam a atividades sem fins lucrativos. Eis a faceta do catolicismo brasileiro para
a qual esta pesquisa se voltou.
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The Integrated Density of States for Operators on GroupsSchwarzenberger, Fabian 18 September 2013 (has links) (PDF)
This thesis is devoted to the study of operators on discrete structures. The operators are supposed to be self-adjoint and obey a certain translation invariance property. The discrete structures are given as Cayley graphs via finitely generated groups. Here, sofic groups and amenable groups are in the center of our considerations. Note that every finitely generated amenable group is sofic. We investigate the spectrum of a discrete self-adjoint operator by studying a sequence of finite dimensional analogues of these operators. In the setting of amenable groups we obtain these approximating operators by restricting the operator in question to finite subsets Qn , n ∈ N. These finite dimensional operators are self-adjoint and therefore admit a well-defined normalized eigenvalue counting function. The limit of the normalized eigenvalue counting functions when |Qn | → ∞ (if it exists) is called the integrated density of states (IDS). It is a distribution function of a probability measure encoding the distribution of the spectrum of the operator in question on the real axis.
In this thesis, we prove the existence of the IDS in various geometric settings and for different types of operators. The models we consider include deterministic as well as random situations. Depending on the specific setting, we prove existence of the IDS as a weak limit of distribution functions or even as a uniform limit. Moreover, in certain situations we are able to express the IDS via a semi-explicit formula using the trace of the spectral projection of the original operator. This is sometimes referred to as the validity of the Pastur-Shubin trace formula.
In the most general geometric setting we study, the operators are defined on Cayley graphs of sofic groups. Here we prove weak convergence of the eigenvalue counting functions and verify the validity of the Pastur-Shubin trace formula for random and non-random operators . These results apply to operators which not necessarily bounded or of finite hopping range. The methods are based on resolvent techniques.
This theory is established without having an ergodic theorem for sofic groups at hand. Note that ergodic theory is the usual tool used in the proof of convergence results of this type.
Specifying to operators on amenable groups we are able to prove stronger results. In the discrete case, we show that the IDS exists uniformly for a certain class of finite hopping range operators. This is obtained by using a Banach space-valued ergodic theorem. We show that this applies to eigenvalue counting functions, which implies their convergence with respect to the Banach space norm, in this case the supremum norm. Thus, the heart of this theory is the verification of the Banach space-valued ergodic theorem. Proceeding in two steps we first prove this result for so-called ST-amenable groups. Then, using results from the theory of ε-quasi tilings, we prove a version of the Banach space-valued ergodic theorem which is valid for all amenable groups.
Focusing on random operators on amenable groups, we prove uniform existence of the IDS without the assumption that the operator needs to be of finite hopping range or bounded. Moreover, we verify the Pastur-Shubin trace formula. Here we present different techniques. First we show uniform convergence of the normalized eigenvalue counting functions adapting the technique of the Banach space-valued ergodic theorem from the deterministic setting.
In a second approach we use weak convergence of the eigenvalue counting functions and additionally obtain control over the convergence at the jumps of the IDS. These ingredients are applied to verify uniform existence of the IDS.
In both situations we employ results from the theory of large deviations, in order to deal with long-range interactions.
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The Integrated Density of States for Operators on GroupsSchwarzenberger, Fabian 14 May 2014 (has links)
This book is devoted to the study of operators on discrete structures. The operators are supposed to be self-adjoint and obey a certain translation invariance property. The discrete structures are given as Cayley graphs via finitely generated groups. Here, sofic groups and amenable groups are in the center of our considerations. Note that every finitely generated amenable group is sofic. We investigate the spectrum of a discrete self-adjoint operator by studying a sequence of finite dimensional analogues of these operators. In the setting of amenable groups we obtain these approximating operators by restricting the operator in question to finite subsets Qn , n ∈ N. These finite dimensional operators are self-adjoint and therefore admit a well-defined normalized eigenvalue counting function. The limit of the normalized eigenvalue counting functions when |Qn | → ∞ (if it exists) is called the integrated density of states (IDS). It is a distribution function of a probability measure encoding the distribution of the spectrum of the operator in question on the real axis.
We prove the existence of the IDS in various geometric settings and for different types of operators. The models we consider include deterministic as well as random situations. Depending on the specific setting, we prove existence of the IDS as a weak limit of distribution functions or even as a uniform limit. Moreover, in certain situations we are able to express the IDS via a semi-explicit formula using the trace of the spectral projection of the original operator. This is sometimes referred to as the validity of the Pastur-Shubin trace formula.
In the most general geometric setting we study, the operators are defined on Cayley graphs of sofic groups. Here we prove weak convergence of the eigenvalue counting functions and verify the validity of the Pastur-Shubin trace formula for random and non-random operators . These results apply to operators which not necessarily bounded or of finite hopping range. The methods are based on resolvent techniques. This theory is established without having an ergodic theorem for sofic groups at hand. Note that ergodic theory is the usual tool used in the proof of convergence results of this type.
Specifying to operators on amenable groups we are able to prove stronger results. In the discrete case, we show that the IDS exists uniformly for a certain class of finite hopping range operators. This is obtained by using a Banach space-valued ergodic theorem. We show that this applies to eigenvalue counting functions, which implies their convergence with respect to the Banach space norm, in this case the supremum norm. Thus, the heart of this theory is the verification of the Banach space-valued ergodic theorem. Proceeding in two steps we first prove this result for so-called ST-amenable groups. Then, using results from the theory of ε-quasi tilings, we prove a version of the Banach space-valued ergodic theorem which is valid for all amenable groups.
Focusing on random operators on amenable groups, we prove uniform existence of the IDS without the assumption that the operator needs to be of finite hopping range or bounded. Moreover, we verify the Pastur-Shubin trace formula. Here we present different techniques. First we show uniform convergence of the normalized eigenvalue counting functions adapting the technique of the Banach space-valued ergodic theorem from the deterministic setting. In a second approach we use weak convergence of the eigenvalue counting functions and additionally obtain control over the convergence at the jumps of the IDS. These ingredients are applied to verify uniform existence of the IDS. In both situations we employ results from the theory of large deviations, in order to deal with long-range interactions.
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M?todo de detec??o massiva de sistemas LS-MIMO empregando o m?todo de Richardson modificado em aceleradores gr?ficosCosta, Haulisson Jody Batista da 22 August 2016 (has links)
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Previous issue date: 2016-08-22 / A evolu??o da comunica??o sem fio traz suporte a m?ltiplos dispositivos que, simultaneamente,
transmitem altas taxas de dados. T?cnicas emergentes de comunica??o LSMIMO
permitem explorar o aumento da capacidade para a moderniza??o dos sistemas
de transmiss?o. Apesar da pr?pria caracter?stica do canal de multipercurso proporcionar
efici?ncia espectral, a complexidade computacional dos m?todos de detec??o LS-MIMO
tornam-se proibitivos em sistemas com elevada quantidades de antenas. Procurando aumentar
a quantidade de antenas empregadas na detec??o MIMO, este trabalho prop?e
adaptar o m?todo iterativo de Richardson ao conceito de matrizes aleat?rias estabelecido
por Marchenko-Pastur e ao conceito de execu??o paralela de modo a adequ?-lo ? aplica??o
em sistema LS-MIMO. O m?todo iterativo de Richardson exige condi??es para
resolu??o linear que restringem sua ampla aplica??o. Contudo, a compreens?o do canal
permite estabelecer adapta??es que suprem as exig?ncias do m?todo. Os efeitos do canal
conceituados por Marchenko-Pastur permitem modificar o m?todo, atrelando a estabilidade
? quantidade de antenas de maneira que o aumento dessa propor??o contribui tanto
para a melhoria da converg?ncia quanto para a redu??o relativa das itera??es. Adicionalmente,
a execu??o compartilhada com o m?todo de decodifica??o proporciona uma
divis?o de carga de trabalho, de modo a permitir uma taxa de transfer?ncia que supera
outros m?todos. Os resultados levantados a partir das an?lises comparativas entre outras
propostas de execu??o paralela mostraram de forma in?dita a capacidade de detec??o em
larga escala. Ainda, a proposta mostrou um n?vel de adaptabilidade que permite variar
a rela??o entre taxa de transfer?ncia de dados e complexidade. Nesse sentido, o m?todo
mostrou que com taxas de transmiss?o equipar?veis com outras propostas permite aumentar
seu desempenho em 150% abdicando 1,75 dB da rela??o sinal ru?do. Baseando-se
nessa abordagem, o sistema mostra um desempenho superior as outras estrat?gias executadas
em GPU que apontam um incremento significativo na capacidade de transmiss?o
paralela. A proposta, tamb?m, mostra aspectos escal?veis que permitem alcan?ar um
desempenho na ordem de Gb=s pela inser??o de outros dispositivos (GPUs) operando
paralelamente no sistema. / The evolution of wireless communications must support multiples devices and maintain
high-speed data transmission. The emerging Large-Scale MIMO techniques allows
improving the capacity for the next generations of communications systems. Although
the benefit of multipath involves the spectral efficiency, the computational complexity of
LS-MIMO detection becomes prohibitive in large systems. Seeking to overcome it, we
propose to adapt the Richardson iterative method to the LS-MIMO with random matrices
theory by concepts of Marchenko-Pastur and parallel executions. This method requires
restricted conditions for the linear resolution that limits its applications. However, the
channel knowledge allows establishing adaptations that supply the requirements of the
method. The channel effect explained by Marchenko-Pastur allows associating the stability
of the process with an increase in the numbers of antennas that contributed to improved
the convergence and reduction the iterations. Furthermore, the shared execution with
decoding blocks provide a workload distribution that surpasses the throughput of others
detections. The results achieved from the comparative analysis of other proposals showed
an unprecedented way to increase capability on the large scale detection and provides
an efficient parallel processing. Also, the proposal demonstrated a level of adaptability
that allows diversifying the association between transmission rate and complexity. Therefore,
the implementation of Richardson detection establishes that the transmission rate
is comparable with other projects and the increasing of 1.74dB SNR improve 150% at
throughput. Based on this approach, the execution shows a significant increase in parallel
transmission capacity when implemented on GPU. Also, the implementation shows scalable
aspects that allow increasing the performance to Gb/s by insertion of others parallels
devices (GPUs) in the system.
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The Integrated Density of States for Operators on GroupsSchwarzenberger, Fabian 06 September 2013 (has links)
This thesis is devoted to the study of operators on discrete structures. The operators are supposed to be self-adjoint and obey a certain translation invariance property. The discrete structures are given as Cayley graphs via finitely generated groups. Here, sofic groups and amenable groups are in the center of our considerations. Note that every finitely generated amenable group is sofic. We investigate the spectrum of a discrete self-adjoint operator by studying a sequence of finite dimensional analogues of these operators. In the setting of amenable groups we obtain these approximating operators by restricting the operator in question to finite subsets Qn , n ∈ N. These finite dimensional operators are self-adjoint and therefore admit a well-defined normalized eigenvalue counting function. The limit of the normalized eigenvalue counting functions when |Qn | → ∞ (if it exists) is called the integrated density of states (IDS). It is a distribution function of a probability measure encoding the distribution of the spectrum of the operator in question on the real axis.
In this thesis, we prove the existence of the IDS in various geometric settings and for different types of operators. The models we consider include deterministic as well as random situations. Depending on the specific setting, we prove existence of the IDS as a weak limit of distribution functions or even as a uniform limit. Moreover, in certain situations we are able to express the IDS via a semi-explicit formula using the trace of the spectral projection of the original operator. This is sometimes referred to as the validity of the Pastur-Shubin trace formula.
In the most general geometric setting we study, the operators are defined on Cayley graphs of sofic groups. Here we prove weak convergence of the eigenvalue counting functions and verify the validity of the Pastur-Shubin trace formula for random and non-random operators . These results apply to operators which not necessarily bounded or of finite hopping range. The methods are based on resolvent techniques.
This theory is established without having an ergodic theorem for sofic groups at hand. Note that ergodic theory is the usual tool used in the proof of convergence results of this type.
Specifying to operators on amenable groups we are able to prove stronger results. In the discrete case, we show that the IDS exists uniformly for a certain class of finite hopping range operators. This is obtained by using a Banach space-valued ergodic theorem. We show that this applies to eigenvalue counting functions, which implies their convergence with respect to the Banach space norm, in this case the supremum norm. Thus, the heart of this theory is the verification of the Banach space-valued ergodic theorem. Proceeding in two steps we first prove this result for so-called ST-amenable groups. Then, using results from the theory of ε-quasi tilings, we prove a version of the Banach space-valued ergodic theorem which is valid for all amenable groups.
Focusing on random operators on amenable groups, we prove uniform existence of the IDS without the assumption that the operator needs to be of finite hopping range or bounded. Moreover, we verify the Pastur-Shubin trace formula. Here we present different techniques. First we show uniform convergence of the normalized eigenvalue counting functions adapting the technique of the Banach space-valued ergodic theorem from the deterministic setting.
In a second approach we use weak convergence of the eigenvalue counting functions and additionally obtain control over the convergence at the jumps of the IDS. These ingredients are applied to verify uniform existence of the IDS.
In both situations we employ results from the theory of large deviations, in order to deal with long-range interactions.
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