Notes, summaries, assignments, exams, and problems for Computers

Network Protocols (नेटवर्क प्रोटोकॉल)

Frame Relay क्या है? (What is Frame Relay in Hindi)

Frame Relay एक तेज गति का packet switching प्रोटोकॉल है जिसका प्रयोग Wide Area Networks (WANs) में किया जाता है। इसके अलावा, यह दो या दो से अधिक Local Area Networks (LANs) के बीच data को transfer करता है।

Frame Relay एक packet switched टेक्नोलॉजी है। इसे Local Area Networks के बीच कम खर्च में data transfer करने के लिए design किया गया था। साथ ही,... Continue reading "Frame Relay क्या है? फायदे और नुकसान (हिंदी में पूरी जानकारी)" »

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

Understanding Computer Fundamentals

Output Devices

Plotter

A plotter is a specialized output device that generates images on paper, similar to a printer but with a distinct approach. Plotters excel at producing large-scale drawings or images, such as construction plans or blueprints. They can be connected to the same port typically used by a printer.

Tab Stops

Tab stops simplify document formatting. By default, they are set at 0.5-inch intervals from the left margin, allowing for easy creation of elements like tables of contents or indexes without manual adjustments.

Formatting and Data Visualization

Importance of Pie Charts

Pie charts effectively illustrate relative proportions or contributions to a whole using a single data series. Their effectiveness... Continue reading "Understanding Computer Fundamentals: Output Devices, Formatting, and Software Features" »

Core Graphic Design Concepts and Terminology

Vector Graphics and File Types

• Vector allows for resizing without loss in quality.
• Vector graphics are smaller in file size.

• PNG file type (Portable Network Graphics).
• SVG (Scalable Vector Graphics).

Digital Asset Sourcing

• He found the images online, but they were in the public domain.
• The team member created the images himself.

The whole is greater than the sum of the parts.

Typography and Text Handling

• Kerning: The spacing between specific pairs of characters.
• Leading: The distance between each line of text.

Font Classifications

• Script
• Decorative
• Serif
• Sans Serif

Text Overflow

Even though it's not visible, the excess text is still in the bounding area, and a small plus (+) symbol is displayed at the bottom of the... Continue reading "Essential Terminology for Graphic Design, Printing, and Web Projects" »

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,

C Programming Basics

Printing a Message

Variables and Mathematical Calculations

Floating-Point Math

Arrays

List and Briefly Define the Four Main Elements of a Computer

A computer is composed of four fundamental elements:

• Main memory: Stores both data and instructions.
• Arithmetic and Logic Unit (ALU): Capable of operating on binary data.
• Control Unit: Interprets the instructions in memory and ensures their execution.
• Input and Output (I/O) Equipment: Operated by the control unit to facilitate interaction with the external world.

Define the Two Main Categories of Processor Registers

Processor registers can be broadly classified into two categories:

• User-Visible Registers: These registers are accessible to programmers using machine or assembly language. They help minimize references to main memory by optimizing register usage. High-level language compilers

• A class is a template used to create objects and declare data types and methods in a program.
• Public - Modifier used to declare classes and interfaces. Void - Method that returns no value. Main - Marks the start and end of program execution.
• Scanner class - Used to get user input for types like String and Int.
• Exceptions: Try-catch block, throw statement.
• Inheritance provides a powerful and natural mechanism for organizing and structuring software programs. It improves clarity in the design of classes.
• A subclass provides specialized behavior based on elements provided by the superclass. Using inheritance, programmers can reuse the code in the superclass many times.
• Reading and Writing to Files:
  1. Import java.io file.
  2. File inputFile = new File("input.

Theory of Computation

Automata Theory

Automata theory is a theoretical branch of computer science and mathematics that deals with the logic of computation using simple machines called automata. The main goal of automata theory is to develop methods for describing and analyzing the dynamic behavior of discrete systems. Automata consist of states (represented by circles) and transitions (represented by arrows).

Finite Automata

A finite automaton is an abstract computing device and a mathematical model of a system with discrete input, output, states, and a set of transitions between states that occur on input symbols from an alphabet. Finite automata are the simplest machines for pattern recognition, used to characterize regular languages, analyze... Continue reading "Theory of Computation: Automata, and Regular Expressions" »