Notes, abstracts, papers, exams and problems of University

SkinnerDB: Regret-Bounded Query Evaluation via Reinforcement Learning

INTRODUCTION AND PROBLEM DEFINITION:

The work is on query optimization, more specifically: SkinnerDB focuses on finding the optimal Join Order. Because it has the most impact in practice.

SkinnerDB aims to get expected near optimal results without needing any a-priori information. It does not make strong assumptions either.

CONTRIBUTIONS:

• Introduced a new quality criterion for query evaluation strategies that compares expected and optimal execution cost.
• Proposed several adaptive execution strategies based on reinforcement learning.
• Formally proved correctness and regret bounds for those execution strategies.
• Experimental comparisations of those strategies, implemented in SkinnerDB,

Acid Rain: Concurrency-Related Attacks in Database-Backed Web Applications

Motivation:

• 12 popular self-hosted e-commerce applications (deployed over 2M websites, representing over 50% of all e-commerce websites)
• 22 critical ACIDRain attacks identified and verified
• Flexcoin -> Bankrupted

Problem Definition:

An application is vulnerable if:

• Anomalies Possible: Under concurrent API access, the application may exhibit behaviors (i.e., anomalies) that could not have arisen under serial execution.
• Sensitive Invariants: The anomalies arising from concurrent access lead to violations of application invariants.

Solution:

• Execute API calls against a live application and database to generate a (possibly sequential) trace of database activity.
• Analyze the trace

Key Properties of Proteins

• Their molecular weight ranges from 1,000 to several hundred thousand.
• Generally water-soluble, with the exception of hydrophilic membrane proteins.
• Absorb light in the UV range, with maximum absorption at 280nm due to the presence of aromatic amino acids.
• Have a specific isoelectric pH (pI). Positively charged below pI, negatively charged above pI.
• Proteins are charged, which depends on the buffer.
• Move under the electric charge and can be separated by electrophoresis.
• Give a color reaction with reagents, such as a blue color with ninhydrin.

Classification of Proteins

Basis of Structure

1. Globular: All enzymes and intracellular proteins are globular, such as myoglobin and hemoglobin.
2. Fibrous: Mostly extracellular, such as collagen.

Circulator

A nonreciprocal device, means transfer function cannot be calculated inverse (output to input). The characteristic of this device depends on which direction the applied signal. It is based on magnetic ferrite and uses a ferrite core.

MW Semiconductor Devices

• Diodes: can be used for detecting MW signals. (Until the 1960s).
• -Schottky pin diodes are passive. Varactor, tunnel are active diodes. Gun impatt, trapatt. You can't use diodes with wires because this wire becomes inductive and stops MW signal. Connect diode chips with wire bonds (without connectors.)
• Schottky barrier diode: there are no minority carriers, so there is no delay (only majority). The operation speed is high, so it can be used in MW applications as a detector.

Cutoff Frequency

Canadian Packaging Requirements

Weight: Imperial system, metric system

Label: Product identity quantity, English and French, manufacturer information

Ingredients: Religious and cultural issues, prohibited, clearly labeled

Legal Requirements: Materials, warning

Centralized Strategy

Means that all of its manufacturing and marketing is performed in one location

Decentralized Strategy

Which means it would set up a manufacturing plant in another nation, or hire a Salesforce there, or even license its brand to a local manufacturer

A Trade Show

A collection of manufacturers and distributors of similar products who rent space, set up display booths, and tell their products to registered buyers who are seeking products to sell in the retail businesses

Licensing

Despite all those advantages a wealth tax has, many countries abolished it because of the high cost of implementation and the little revenue it generated. There are high administrative costs and complex annual tax returns linked to the wealth tax, which make it less efficient. Also, sometimes it is quite difficult to measure wealth. Values can be misrepresented and in a lot of cases, it is not possible to know the real value of an asset until it is sold.

Furthermore, the argument of double taxation can be applied to the wealth tax. If wealth is accumulated from salaries, savings, or personal business income, double taxation is likely to happen since these flows in many cases have already been taxed. This argument, though, can be used for almost... Continue reading "The Pros and Cons of Wealth Tax: Efficiency, Double Taxation, and Capital Flight" »

1. Introduction: The European Union

Important dates: 7 enlargements:
- UK, Ireland, Denmark (1973)
- Greece (1981)
- Portugal and Spain (1986)
- Finland, Sweden, Austria (1995)
- 10 countries (2004)
- Bulgaria and Romania (2007)
- Croatia (2013)

7 treaties:
1. Treaty of Paris (1950): European Coal and Steel Community
2. Treaty of Rome (1957): EURATOM, EEC, ECSC.
3. Treaty of the European Single Act (1986): the Single Market.
4. Treaty of Maastricht (1991): the Treaty of the EU.
5. Treaty of Amsterdam (1996)
6. Treaty of Nice (2001)
7. Treaty of Lisbon (2009)

1 downsizing: Brexit (2019-?)

Aspects of the European Integration Model - Mechanisms:
- Single market.
- Customs Union.
- Single currency.
- European institutions.
- Interterritorial cohesion policies.
- Common... Continue reading "Understanding the European Union and Its Monetary Union" »