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

1. Client Initiation and DNS Lookup

• The user enters a URL or clicks a link in the browser. The browser parses the URL and extracts the domain (e.g., www.example.com).

• A **DNS lookup** translates this domain into an IP address—acting like a digital phonebook entry.

2. Establishing the TCP Connection

The browser’s operating system (OS) creates a socket and initiates the **TCP three-way handshake** with the server:

1. SYN: Client sends a synchronization request to the server.
2. SYN-ACK: Server acknowledges the request and sends its own synchronization.
3. ACK: Client acknowledges the server's response.

Once this handshake is complete, a full-duplex TCP connection is open and ready for reliable data exchange.

3. Sending the HTTP Request Message

The client constructs... Continue reading "The Complete HTTP Request Lifecycle Explained Step-by-Step" »

Python Functions: Definition, Need, and Example

A function is a block of organized and reusable program code that performs a single, specific, and well-defined task. Python enables its programmers to break up a program into functions, thereby insulating the code of one function from the codes of other functions. A function f that uses another function g is known as the calling function, and g is known as the called function.

Need for Functions:

• Code Reusability: Functions allow you to write a block of code once and reuse it multiple times, avoiding redundancy.
• Modularity: They break down complex problems into smaller, manageable parts, making the program easier to understand, debug, and maintain.
• Improved Readability: Well-defined functions make

What is Mathematical Logical Thinking?

These are the skills students develop associated with logical and mathematical concepts, reasoning, comprehension, and exploration of the world through real proportions, thus strengthening more abstract aspects of thought.

Geometry with Dinosaurs

This activity involves cutting out various geometric shapes with EVA rubber. Children will then create their own dinosaurs using these shapes. Through this activity, they can learn geometric shapes, count the number of elements used in each dinosaur (like the sides of the shapes), and create new geometric shapes from the ones they already have.

Logical Reasoning with Chupa Chups

This activity consists of creating logically structured material and playing with it using... Continue reading "Developing Logical and Mathematical Thinking in Children" »

.NET Framework and Its Core Components

The Microsoft .NET Framework is a comprehensive and consistent programming model developed by Microsoft for building applications with visually stunning user experiences, seamless and secure communication, and the ability to model a range of business processes. The .NET Framework is a software development platform used for building and running Windows applications. It provides a controlled programming environment where software can be developed, installed, and executed primarily on Windows-based operating systems.

Key Components of .NET Framework:

1. Common Language Runtime (CLR): The CLR is the execution engine for .NET applications. It provides core services such as:
   • Memory management (garbage collection)
   • Thread

This educational resource details Ethereum, a decentralized blockchain platform launched in 2015, focusing on its key features, accounts, smart contracts, transactions, and consensus mechanisms.

Ethereum Fundamentals

Ethereum is a blockchain platform that supports smart contracts—immutable computer programs executed on the Ethereum Virtual Machine (EVM). It uses Ether (ETH) as its native cryptocurrency to pay for transaction processing and smart contract execution.

Ethereum Accounts and Wallets

Account Types

• Externally-Owned Accounts (EOAs): Controlled by private keys, used primarily for transactions like ETH transfers. Public keys are derived using Elliptic Curve Cryptography (ECC).
• Contract Accounts: Controlled by smart contract code, deployed

This document presents two distinct approaches to solving the Traveling Salesperson Problem (TSP) using Prolog: an exact, brute-force method and a heuristic-based Nearest Neighbor algorithm. Both implementations are demonstrated with code and sample queries.

Exact Solver: Brute-Force TSP Algorithm

This section details a Prolog program that finds the optimal (shortest) path for the Traveling Salesperson Problem by generating and evaluating all possible tours. This method guarantees the optimal solution but can be computationally intensive for larger sets of cities.

Defining City Distances in Prolog

The distances between cities are defined using dist/3 facts. The predicate is made symmetric to ensure that dist(X,Y,D) implies dist(Y,X,D).

dist(a,b,

Performance Metrics

• Elapsed Time: Represents overall system performance. It is the total time taken to complete a task.
• User CPU Time: Indicates CPU performance. It is the time the task actively runs on the CPU, excluding idle time.
• CPU Time: The time the CPU spends executing instructions, either from the task or the operating system, excluding idle time.
• Clock Speed: 1 MHz equals 1 million clock cycles per second. 1 GHz equals 1 billion clock cycles per second.
• Response Time: Equivalent to execution time.
• Throughput: Equivalent to bandwidth.
• Performance Comparison: (PerfA) / (PerfB) = (ExecTimeB) / (ExecTimeA) = n

Impact of Processor Upgrades

• Replacing a processor with a faster one decreases response time and increases throughput.
• Adding an additional

Implementação da Transposição de Matriz 4x4 em C

Este programa em C demonstra como calcular e exibir a matriz transposta (B) de uma matriz quadrada de ordem 4 (A). A transposição é realizada trocando as linhas pelas colunas, ou seja, o elemento na posição A[i][j] é copiado para B[j][i].

Código Fonte em C para Transposição de Matriz

O código utiliza as bibliotecas padrão stdio.h para entrada/saída e conio.h (comum em ambientes legados) para controle de console.

#include <stdio.h>
#include <conio.h>

int main()
{
    int i, j, A[4][4], B[4][4];

    // 1. Entrada de Dados
    printf("Insira os elementos da Matriz A (4x4):\n");
    for(i = 0; i < 4; i++)
    {
        for(j = 0; j < 4; j++)
        {
            printf(

Building Java GUI Applications with AWT

Creating GUI applications using Abstract Window Toolkit (AWT) involves setting up a top-level container, adding components, arranging them with a Layout Manager, and making the container visible.

Steps to Create an AWT Application

1. Choose a Top-Level Container

The application needs a primary window to hold all components. The most common choice is the Frame class, which provides a title bar, borders, and window controls.

import java.awt.*;

// Class extends Frame to be the application window itself
public class AWTExample extends Frame {
    // Constructor and other methods
}

2. Initialize the Container (The Frame)

Inside the constructor, you set up the basic properties of the window:

• Title: Set the window

Core Database Concepts and Relational Algebra

Question 1: Cartesian Product Size

Question 1: S is a relation instance. If S has 6 tuples, how many tuples are there in the result of the following SQL query?

SELECT * FROM S S1, S S2;

Answer: 36 (Calculated as 6 * 6, representing the Cartesian product of S with itself.)

Question 2: Maximum Tuples and Primary Keys

Question 2: Let R(A, B, C, D) be a relation, where (A, B, C) is the Primary Key (PK) of R, and attribute D cannot be NULL. Assume A's domain has 5 different values, B's domain has 2, C has 4, and D has 3. What is the maximum number of tuples that can be in an instance of R?

Answer: 40 (Calculated as 5 * 2 * 4. The maximum number of tuples is determined by the product of the domain sizes of the... Continue reading "Database Fundamentals: SQL Queries and Relational Concepts" »