Saturday, April 27, 2024 at 5:30 PM
- written by user ΑΡΒΑΝΙΤΗΣ ΣΤΥΛΙΑΝΟΣ

We have completed the relation of uniform convergence with the approximation of optimization problems by focusing on the asymptotic behavior of optimizers. We have proceeded with the examination of the notions of  completeness and Lipschitz continuity, and contraction mappings.
 

Notes for the above can be found herehere and here. The whiteboards from analogous Ac. year's 2020-21 lectures (please keep in mind that those are not necessarily identical to the current lectures but they contain som

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Sunday, April 21, 2024 at 11:48 PM
- written by user ΑΡΒΑΝΙΤΗΣ ΣΤΥΛΙΑΝΟΣ

We provided a brief reminder of  topological notions in metric spaces with emphasis on the notion of (sequential) convergence and function continuity. Specifying the above in functional speces equipped with the uniform metric we have focused on the notion of uniform functional convergence constrasting it to the (generically non metrizable) notion of pointwise convergence. We then focused on a major application: the approximation of optimization problems.

Notes for the above can be found here and

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Saturday, April 6, 2024 at 3:59 PM
- written by user ΑΡΒΑΝΙΤΗΣ ΣΤΥΛΙΑΝΟΣ

We have continued with our application of the notion of total boundedness in asymptotic analysis: the derivation of a Uniform Law of Large Numbers in a simple framework using a chaining argument that makes use of finite coverings. We have constructed examples of totally bounded sets via the notion of covering numbers.

Notes on the above can be found here. Notes on the particular ULLN application can be found here

The whiteboards from analogous lectures from the Av. Year 2020-21 (please keep in

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Sunday, March 31, 2024 at 6:31 PM
- written by user ΑΡΒΑΝΙΤΗΣ ΣΤΥΛΙΑΝΟΣ

We begun with an equivalent definition that is useful for the introduction of total boundness. Strenghtening thus, the boundedness characterization we have introduced the notion of total boundness. We have started  our examination of the latter. We have given properties, e.g. that the centers of the covering balls can be chosen inside the totally bounded set, as well as (trivial) examples-counterexamples (the analytical complexity of the notion clearly manifested itself on that counter examples

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Saturday, March 23, 2024 at 7:05 PM
- written by user ΑΡΒΑΝΙΤΗΣ ΣΤΥΛΙΑΝΟΣ

We continued our study of the notion of boundedness. We have proven that the center of the covering ball need not be an element of the subset at hand although we have shown that when such a ball exists the center can always be chosen to lie inside this subset. We have shown that any finite set is (universally) bounded. We have proven that if a space is bounded w.r.t. a dominant metric, then it is also bounded w.r.t. to the dominated one. An obvious corollary is that equivalent metrics totally ag

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Saturday, March 16, 2024 at 5:35 PM
- written by user ΑΡΒΑΝΙΤΗΣ ΣΤΥΛΙΑΝΟΣ

We have provided with the geometric realizations of open and closed balls in gif.latex?%5Cmathbb%7BR%7D%5E%7Bn%7D endowed with any of the three "commonly examined" metrics,  showed that the “geometry” of the open (and/or the closed) balls crucially depends on the metric. Their geometric relations were later on exemplified via the notion of metric equivalence and its balls' implications. We thus examined the antimonotonic relationship between balls of the same centered arising by pairs of dominant and dominating metrics.

We begun o

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Saturday, March 9, 2024 at 1:14 AM
- written by user ΑΡΒΑΝΙΤΗΣ ΣΤΥΛΙΑΝΟΣ

We continued examining subexamples inside the important example of the space of bounded real functions on a non-empty domain endowed with the uniform metric.

We begun studying properties of metric spaces via the definition of the open and the closed balls that the metric defines. We have shown that these cannot in any case be empty, and obey some monotonicity property. The examples of the real line endowed with the usual metric, the real line endowed with the "exponential metric", the real line

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Saturday, March 2, 2024 at 5:33 PM
- written by user ΑΡΒΑΝΙΤΗΣ ΣΤΥΛΙΑΝΟΣ

We have investigated the further relation notion between metrics on the same carrier set; two suchlike metrics are considered equivalent whenever the first dominates the second and vice versa. Hence two such metrics can be considered equivalent-and suspected of introducing "similar properties" on the same carrier-without being necessarily equal as functions.

We examined the important-to the upcoming lectures-example of the space of bounded real functions on a non-empty domain endowed with the un

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Monday, February 26, 2024 at 1:03 AM
- written by user ΑΡΒΑΝΙΤΗΣ ΣΤΥΛΙΑΝΟΣ

We continued the investigation of examples involving metrics on sets of finite dimensional real vectors. (Some of) The examples have shown that it is possible that different metrics on the same carrier set can obey relations, e.g. in the form of functional inequalities. We suspected that such relations might imply analogous ones between the relevant properties that each metric endows the space with, and that provides as with a motivation of further examination of such relations.

Notes on the pre

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Monday, February 19, 2024 at 12:03 AM
- written by user ΑΡΒΑΝΙΤΗΣ ΣΤΥΛΙΑΝΟΣ

After generalizing our basic definitions with the notions of a pseudo-metric and the subsequent notion of a psedo-metric space, as well as with the notion of a metric-subspace, we begun the examination of examples of metrics on spaces comprised of real (finite dimensional) vectors, including the Hamming distance. Our examples showed that several distinct metric spaces (over the same carrier) can become identical when restricted on particular sub-spaces.

Notes on the previous here, and a countere

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