Reliacinė algebra ir norminės formos

Kai kurie žymėjimai ir reliacinė algebra R={A1,A2,...,An} t.y, R yra lentelės L atributų aibė. Ai kur i=1,...,n yra lentelės atributas. Tada L(R) yra lentelės reliacinė schema. Lentelės eilučių aibę žymima l={e1,e2,...,em} kur n - lentelės stulpelių skaičius, m - lentelės eilučių skaičius. Kiekviena eilutė yra sutvarkytas reikšmių rinkinys ej = <a1,a2,...,an> ∈ l; ai ∈ dom(Ai), kur dom(Ai) yra atributo Ai domenas t.y, galimų reikšmių aibė. i=1,...,n j=1,...,m Atributų rinkinys apibūdinantis bet kurią lentelės eilutę yra vadinamas viršrakčiu. Viršraktis yra raktas jei pašalinus bent vieną atributą jis praranda universalumą. Taigi…

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First design for 3d printer
Hex key T handle Drawing

First design for 3d printer

My first design for 3d printing! You can find it on a thigverse: https://www.thingiverse.com/thing:3560965 So that is why it might be a bit over engineered, bu hey, it is fun so who cares ;) I had some hex type key for automatic yard gate engine disabling and it that plastic handle that got broken over time. So I figured out that this fix could be a good practice to learn Fusion and make my own handle design. Some design decisions and conclusions if they have worked out or not: Hex key…

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8086 disassembler using 64 bit assembly language

8086 disassembly application. Project done during computer architecture course. Project is done using nasm(yasm) 64 bit assembly and some c functions to handle input/output. I have chosen such technologies because I was curious about few topics: Learning about asm 64 bit programming Compiling assembly executable for windows 64 platform. During the comp architecture course we were doing assembly programming for a ms dos using dosbox. I was interested in making some executable code on a windows 64 platform. Linking assembly code to some higher lever programming language library. During the…

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Ubuntu install Clojure

sudo apt install default-jre sudo apt install openjdk-11-jre-headless sudo apt install openjdk-8-jre-headless sudo apt install leiningen lein repl //Install IntelliJ IDEA snap install intellij-idea-community --classic --edge intellij-idea-communituy

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Program to find GCD of two polynomials

The objective is to write a program that finds greatest common divisor of two polynomials g(x) and h(x). The task does not define what form we get those two polynomials, so let's say we will get them in a form of a String, something like that: $latex ``2x^3+5x^2+8x+3``$ Let's start splitting our problem into chunks and gather some information about the steps we would need to implement. First, what is the greatest common divisor? In math, GCD of two or more integers, which are not all zero, is the largest positive…

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Removing supervisor password (SVP) on ThinkPad T42

Recently received two ThinkPad T42 laptops ( some company decided to upgrade its IT and were giving away them almost for free ). After turning them on got an 271 error and later was prompted to enter password. It seems battery was dead on both of those laptops and when its dead, real time clock goes bananas and you are asked for supervisor password to set the clock again ( if supervisor password was set ). Offcourse nobody knew anything about what password it was. So had to figure it out…

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ZX Spectrim 128 +3 composite video output and drive belt replacement

Did some work on ZX Spectrum 128 +3 I have. One thing was I wanted to make it work with small "TFT Color monitor" (for a car rear view). This monitor has a composite video input. First I tried using CSYNK and GND signals for a composite video input. You get the video but it was terrible quality. It seems that "The 128 ZX Spectrums including the +3 (and +2A, +2B) have audio sound modulated onto the video, which reduces the clarity of the composite signal that is available at…

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