This dissertation attempts to interpret the statements of Ludwig Mies vans der Rohe (1886-1969) that pertain to his lifelong theory of Baukunst, or the art of building in terms of tectonics. In order to use the concept tectonics as a criterion according to which one can comprehend Mies words and works, this dissertation attempted to define tectonics in a more general sense by collecting existing definitions and categorizing them. The result of this endeavor showed that tectonics does not signify a supportive structure but the art of framing construction, in which linear elements are put together with joints and clad or infilled with lightweight material. It is proposed that Mies, who called the ideal of tectonic architecture the art of building, during his lifelong career, experienced two periods of critical awareness through which he established his own type of tectonic buildings: awareness of the open plan and then that of clear space. After the former occurred in 1926, he focused on the creation of inner spatial openness; after the latter, which this dissertation proposes occurred around 1930, when he met Karlfried Graf Drckheim (1896-1988), who had been absorbed in Lao-tzus philosophy, Mies intended to show that his architectural concern was beyond physical construction by employing the concept of changing nature and by designing his buildings to be neutral frames. Mies finally achieved a tectonically integrated body of a building that contained extroverted and undetermined space, which he referred to as clear space, or generally called Mies universal space, through his lifelong pursuit for the accomplishment of his own art of building, which this dissertation terms Miesian tectonics.

We study the relationship of dominance for sequences and trees in Banach spaces. In the context of sequences, we prove that domination of weakly null sequences is a uniform property. More precisely, if $(v_i)$ is a normalized basic sequence and $X$ is a Banach space such that every normalized weakly null sequence in $X$ has a subsequence that is dominated by $(v_i)$, then there exists a uniform constant $C\geq1$ such that every normalized weakly null sequence in $X$ has a subsequence that is $C$-dominated by $(v_i)$. We prove as well that if $V=(v_i)_{i=1}^\infty$ satisfies some general conditions, then a Banach space $X$ with separable dual has subsequential $V$ upper tree estimates if and only if it embeds into a Banach space with a shrinking FDD which satisfies subsequential $V$ upper block estimates. We apply this theorem to Tsirelson spaces to prove that for all countable ordinals $\alpha$ there exists a Banach space $X$ with Szlenk index at most $\omega^{\alpha \omega +1}$ which is universal for all Banach spaces with Szlenk index at most $\omega^{\alpha\omega}$.

The dissertation thesis consists of two thematic parts. The first part, i.e. chapters 2, 3 and 4, contains results concerning the topic of a new book of the supervisor and coauthors V. Kanovei and M. Sabok "Canonical Ramsey Theory on Polish Spaces". In Chapter 2, there is proved a canonization of all equivalence relations Borel reducible to equivalences definable by analytic P-ideals for the Silver ideal. Moreover, it investigates and classifies sube- quivalences of the equivalence relation E0. In Chapter 3, there is proved a canonization of all equivalence relations Borel reducible to equivalences de- finable by Fσ P-ideals for the Laver ideal and in Chapter 4, we prove the canonization for all analytic equivalence relations for the ideal derived from the Carlson-Simpson (Dual Ramsey) theorem. The second part, consisting of Chapter 5, deals with the existence of universal and ultrahomogeneous Polish metric structures. For instance, we construct a universal Polish metric space which is moreover equipped with countably many closed relations or with a Lipschitz function to an arbitrarily chosen Polish metric space. This work can be considered as an extension of the result of P. Urysohn who constructed a universal and ultrahomogeneous Polish metric space.