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

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Machine Learning Algorithms and Use Cases

Classified in Computers

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AlgorithmTrain or TestUse CasesSupervisedPipe?File TypeCPU or GPU
AutoGluon-Tabulartraining and (optionally) validationAutoGluon-Tabular succeeds by ensembling multiple models and stacking them in multiple layers.YNCSVCPU or GPU (single instance only) M5
BlazingTexttrainText Classification can be used to solve various use-cases like sentiment analysis, spam detection, hashtag predictionYYText file (one sentence per line with space-separated tokens)CPU or GPU (single instance only) M5
CatBoosttraining and (optionally) validationGradientBoosting Regression Neural Network, Gradient Boosting is best useful when the number of dimensions in the data is less , when a simple linear model performs very badly,YNCSVCPU (single instance only)
DeepAR Forecastingtrain
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SkinnerDB: Reinforcement Learning for Query Optimization

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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,
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C Programming Basics: Examples and Explanations

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C Programming Basics

Printing a Message

int main() { print("Hello!!!"); }

Variables and Mathematical Calculations

int main() // Main function

{

int a = 25; // Initialize a variable to 25

int b = 17; // Initialize b variable to 17

int c = a + b; // Initialize c variable to a + b

print("c = %d ", c); // Display decimal value of c

}

Floating-Point Math

int main() // Main function

{

float r = 1.0; // Set radius to 1.0

float c = 2.0 * PI * r; // Calculate circumference

print("circumference = %f \n", c); // Display circumference

}

Arrays

int main() // Main function

{

int p[] = {1, 2, 3, 5, 7, 11}; // Initialize the array

print("p[0] = %d\n", p[0]); // Display what p[0] stores

print("p[3] = %d\n", p[3]); // Display what p[3] stores

p[3] = 101; // Assignment

}

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Understanding Key Computer Science Concepts

Posted by Lijia and classified in Computers

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Fetch-Execute Cycle

  1. The address in the program counter is transferred within the CPU to the Memory Address Register (MAR).
  2. During the next clock cycle, two things happen simultaneously:
    • The instruction held in the address pointed to by the MAR is fetched into the Memory Data Register (MDR).
    • The address stored in the program counter is incremented.
  3. The instruction stored in the MDR is transferred within the CPU to the Current Instruction Register (CIR).

Sound Sampling

  1. The amplitude of the sound wave is determined to get an approximation of the sound wave.
  2. This is encoded as a sequence of binary numbers and converted to a digital signal.
  3. Increasing the sampling rate will improve the accuracy of the recording.

Run-Length Encoding (RLE)

  1. RLE is a lossless
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Understanding Computer Architecture: Key Components and Functions

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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

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Java Programming Concepts: A Comprehensive Guide

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  • 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.
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Theory of Computation: Automata, and Regular Expressions

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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" »

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Data Manipulation and Visualization with R and the nycflights13 Dataset

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library(nycflights13)
library(tidyverse)

Data Manipulation with dplyr

Ordering Rows with arrange()

arrange(flights, year, month, day)
arrange(flights, desc(arr_delay))

Handling NAs

df <- tibble(x = c(5, 2, NA))
arrange(df, x)
arrange(df, desc(x))

Selecting Columns with select()

select(flights, year, month, day)
select(flights, year:day)
select(flights, -(year:day))
rename(flights, mes = month)
select(flights, time_hour, air_time, everything())

Creating New Variables with mutate()

flights_sml <- select(flights, year:day, ends_with("delay"), distance, air_time)
mutate(flights_sml, gain = arr_delay - dep_delay, speed = distance / air_time * 60)

Creating Functions with Vector Arguments

transmute(flights, dep_time, hour = dep_time %/% 100, minute = dep_time %
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Digital Logic Design: Examples in VHDL

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Behavioral Architecture of a State Machine

This VHDL code describes the behavioral architecture of a state machine.

TYPE tipo_estado IS (DET0, DET0a1, DET1a0, DET1);
signal Estado_actual : tipo_estado;
signal Estado_siguiente : tipo_estado;
begin
Registro_estado: process (clk, reset)
begin
if reset='1' then Estado_actual <= DET0;
elsif (clk'event and clk='1') then
Estado_actual <= Estado_siguiente;
end if;
end process Registro_estado;
Cambio_Estado: process (Dato, Estado_actual)
begin
Estado_siguiente <= Estado_actual;
case Estado_actual is
when DET0 => if (Dato='1') then Estado_siguiente <= DET0a1;
else Estado_siguiente <= DET0;
end if;
when DET0a1 => if (Dato='1') then Estado_siguiente <= DET1;
else Estado_siguiente <= DET1a0;
end if;
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Microcontrollers: Architecture, Instruction Sets, and Interfacing

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Microcontrollers, Microcomputers, and Microprocessors

Microcontroller: Processor, memory, and I/O ports integrated on a single chip.

Microcomputer: A small computer.

Microprocessor: Example: Intel x86.

Von Neumann Architecture

Components:

  • Processor (Control Unit, ALU, Registers)
  • Memory (RAM - Volatile, ROM - Non-Volatile)
  • I/O

A single bus interconnects the processor, memory, and I/O.

RISC vs. CISC

FeatureCISCRISC
Instruction SetComplex Instruction Set ComputerReduced Instruction Set Computer
InstructionsMulti-cycle, complex instructionsMostly single-cycle, reduced instructions
Instruction TypesMany, varying lengthFew, fixed length
ComplexityHardwareSoftware
Code SizeSmallLarge
ExamplesIntel (x86), Freescale 9S12MIPS, ARM, SPARC, PowerPC

RAM vs. ROM vs. CPU Register

FeatureRAMROM
ElaborationRandom
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