Recent changes · Kostas Maistrelis

Recent changes · Kostas Maistrelishttps://en.maistrelis.com/changelog/Recent changesenKostas MaistrelisKostas MaistrelisMon, 06 Jul 2026 19:33:33 +0300Linguisticshttps://en.maistrelis.com/items/linguistics/Mon, 06 Jul 2026 19:33:33 +0300Kostas Maistrelishttps://en.maistrelis.com/items/linguistics/<p> <p>The scientific study of language.</p> </p>Etymologyhttps://en.maistrelis.com/items/etymology/Mon, 06 Jul 2026 19:33:33 +0300Kostas Maistrelishttps://en.maistrelis.com/items/etymology/<p> <p>The study of the history of words, their origins, and how their form and meaning have changed over time.</p> </p>Linguistics -- Etymologyhttps://en.maistrelis.com/items/linguistics-etymology/Mon, 06 Jul 2026 19:33:33 +0300Kostas Maistrelishttps://en.maistrelis.com/items/linguistics-etymology/Lobsterhttps://en.maistrelis.com/items/astakos/Mon, 06 Jul 2026 14:43:30 +0300Kostas Maistrelishttps://en.maistrelis.com/items/astakos/<p> <p>Lobster (an animal species).</p> <p>More specifically, in the Greek region we have:</p> <ul> <li>the «spiny lobster» (Palinurus), which bears two large antennae instead of claws and which the French call «langouste».</li> </ul> <p>Other lobster species are:</p> <ul> <li>the «true lobster» (homard).</li> <li>the American lobster.</li> </ul> </p>Philosophyhttps://en.maistrelis.com/items/filosofia/Mon, 06 Jul 2026 14:38:24 +0300Kostas Maistrelishttps://en.maistrelis.com/items/filosofia/<p> <p>The study of the principles of existence, knowledge, and ethics.</p> </p>Mathematicshttps://en.maistrelis.com/items/mathematics/Mon, 06 Jul 2026 14:34:33 +0300Kostas Maistrelishttps://en.maistrelis.com/items/mathematics/<p> <p>The abstract study of numbers, quantities, structures, and relations.</p> </p>Statisticshttps://en.maistrelis.com/items/statistics/Mon, 06 Jul 2026 14:29:43 +0300Kostas Maistrelishttps://en.maistrelis.com/items/statistics/<p> <p>The study of the collection, analysis, interpretation, and presentation of data.</p> </p>Mathematics -- Derivativehttps://en.maistrelis.com/items/mathimatika-paragogos/Mon, 06 Jul 2026 14:29:43 +0300Kostas Maistrelishttps://en.maistrelis.com/items/mathimatika-paragogos/Exponential Population Growth — From Water Lilies to the Differential Equationhttps://en.maistrelis.com/items/exponential-growth/Mon, 06 Jul 2026 14:29:43 +0300Kostas Maistrelishttps://en.maistrelis.com/items/exponential-growth/<p> <p>Source (R Markdown) and knitted HTML of the lesson «Exponential Population Growth».</p> </p>Exponential Population Growth — From Water Lilies to the Differential Equationhttps://en.maistrelis.com/articles/exponential-growth/Mon, 06 Jul 2026 14:29:43 +0300Kostas Maistrelishttps://en.maistrelis.com/articles/exponential-growth/How, starting from a simple observation — a 10% daily increase in the water lilies of a lake — we arrive at the exponential growth formula by way of a differential equation. A standalone R Markdown lesson with text, R code, plots and mathematics.Logistic Population Growth — When Space Starts to Matterhttps://en.maistrelis.com/items/logistic-growth/Mon, 06 Jul 2026 14:29:43 +0300Kostas Maistrelishttps://en.maistrelis.com/items/logistic-growth/<p> <p>Source (R Markdown) and knitted HTML of the lesson «Logistic Population Growth».</p> </p>Logistic Population Growth — When Space Starts to Matterhttps://en.maistrelis.com/articles/logistic-growth/Mon, 06 Jul 2026 14:29:43 +0300Kostas Maistrelishttps://en.maistrelis.com/articles/logistic-growth/From the exponential to the logistic equation: how the carrying capacity K of the environment turns unchecked growth into a sigmoidal curve. A standalone R Markdown lesson with qualitative analysis, phase portrait, numerical solution (deSolve) and parameter estimation.Population Dynamics — From the Derivative to the Logistic Equationhttps://en.maistrelis.com/collections/dynamiki-plithysmon/Mon, 06 Jul 2026 14:29:43 +0300Kostas Maistrelishttps://en.maistrelis.com/collections/dynamiki-plithysmon/<p> <p>A series of (R Markdown) lessons built step by step: first the concept of the <strong>derivative</strong> as a rate of change, then <strong>exponential</strong> population growth via a differential equation, and finally the <strong>logistic</strong> equation when space and resources impose limits. Best read in order.</p> </p>Douglas Adamshttps://en.maistrelis.com/items/douglas-adams/Mon, 06 Jul 2026 13:58:46 +0300Kostas Maistrelishttps://en.maistrelis.com/items/douglas-adams/<p> <p>British science fiction writer and humorist (1952-2001).</p> </p>Normal Distributionhttps://en.maistrelis.com/items/normal-distribution/Mon, 06 Jul 2026 12:12:18 +0300Kostas Maistrelishttps://en.maistrelis.com/items/normal-distribution/<p> <p>A subcategory of statistics: the Gaussian distribution (the bell curve).</p> </p>opensourcehttps://en.maistrelis.com/items/opensource/Mon, 06 Jul 2026 09:36:43 +0300Kostas Maistrelishttps://en.maistrelis.com/items/opensource/Kosmemophobiahttps://en.maistrelis.com/garden/kosmemophobia/Mon, 06 Jul 2026 03:43:35 +0300Kostas Maistrelishttps://en.maistrelis.com/garden/kosmemophobia/<p>Kosmemophobia is the intense and persistent fear, aversion, or discomfort toward jewelry, such as rings, earrings, necklaces, or bracelets. It can appear at the sight, touch, or use of them and, in more serious cases, lead to avoidance of people or places where jewelry is present.</p> <p>The term is a Greek coinage: κόσμημα (kósmima), meaning «jewel» or «ornament», joined with the suffix -φοβία (-phobia, from φόβος, phóbos, «fear»). Literally, then, it is the fear of jewelry.</p>Argument structurehttps://en.maistrelis.com/garden/epixirima_domi/Mon, 06 Jul 2026 00:30:15 +0300Kostas Maistrelishttps://en.maistrelis.com/garden/epixirima_domi/<p><img src="https://en.maistrelis.com/garden/epixirima_domi/media/epixeirima.en.jpg" alt="argument"> </p> <h2 id="-sound-argument">✅ Sound argument</h2> <p>A sound argument is one that rests on true premises and valid reasoning.</p> <h3 id="premises">Premises:</h3> <ul> <li>All cats are mammals.</li> <li>Whiskers is a cat.</li> </ul> <h3 id="conclusion">Conclusion:</h3> <ul> <li>Whiskers is a mammal.</li> </ul> <h2 id="-rewriting-the-argument-with-variables">🔢 Rewriting the argument with variables</h2> <h3 id="premises-1">Premises:</h3> <ul> <li>All ① are ②.</li> <li>③ is a ①.</li> </ul> <h3 id="conclusion-1">Conclusion:</h3> <ul> <li>③ is a ②.</li> </ul> <p>Every argument of this form is sound, regardless of what the variables stand for, as long as the premises are true. Reasoning of this form is valid, so it guarantees that the conclusion will be true.</p>LLM Skills vs Docs vs Memoryhttps://en.maistrelis.com/garden/llm-skills-vs-docs-vs-memory/Sun, 05 Jul 2026 16:18:05 +0300Kostas Maistrelishttps://en.maistrelis.com/garden/llm-skills-vs-docs-vs-memory/<p>Three ways to give an AI coding agent (e.g. Claude Code) persistent knowledge. They are <strong>not interchangeable</strong> — each answers a different question.</p> <blockquote> <p><strong>One-line mental model:</strong> doc = what I know · skill = what I do · memory = what I remember about you.</p> </blockquote> <h2 id="the-three-at-a-glance">The three at a glance</h2> <table> <thead> <tr> <th></th> <th>Where it lives</th> <th>Shared / in repo?</th> <th>Nature</th> <th>When it loads into context</th> </tr> </thead> <tbody> <tr> <td><strong>memory</strong></td> <td>outside the repo, private to the agent</td> <td>no</td> <td>about <em>you</em> / the working relationship + status</td> <td>an always-on index; details on recall</td> </tr> <tr> <td><strong>doc</strong></td> <td>in the repo (<code>doc/…</code>)</td> <td>yes</td> <td><strong>reference</strong> — how & why something works</td> <td>on-demand (the agent opens the file)</td> </tr> <tr> <td><strong>skill</strong></td> <td>in the repo (<code>.claude/skills/<name>/</code>)</td> <td>yes</td> <td><strong>procedure</strong> — do X, these steps</td> <td>trigger always-on; body on-demand; <code>/</code>-invocable</td> </tr> </tbody> </table> <h2 id="doc--passive-reference">Doc — passive reference</h2> <p>A Markdown file in the codebase. It just sits there, entering the agent’s context only when someone explicitly reads it (or a top-level index points to it and the agent opens it).</p>Playgroundhttps://en.maistrelis.com/garden/playground/Sun, 05 Jul 2026 14:27:42 +0300Kostas Maistrelishttps://en.maistrelis.com/garden/playground/<p>A scratch page — a quick reference for how the basic Markdown structures compose, and a live sample to eyeball the site’s styling (tables especially). English-only by design.</p> <h2 id="text-formatting">Text formatting</h2> <p>Plain text with <strong>bold</strong>, <em>italic</em>, <em><strong>bold italic</strong></em>, <code>inline code</code>, <del>strikethrough</del>, and an <a href="https://en.maistrelis.com/garden/">internal link to the digital garden</a> . External links get the ↗ marker, e.g. <a href="https://gohugo.io/" class="external-link">Hugo</a> .</p> <h2 id="headings">Headings</h2> <p>Use <code>#</code> through <code>######</code>. On this site the note title is the <code><h1></code>, so bodies start at <code>##</code>.</p>Derivativehttps://en.maistrelis.com/items/paragogos/Sun, 05 Jul 2026 01:50:11 +0300Kostas Maistrelishttps://en.maistrelis.com/items/paragogos/<p> <p>The rate of change of a function — how fast it changes.</p> </p>Introduction to Derivatives — A Car on the Roadhttps://en.maistrelis.com/items/eisagogi-paragogos/Sun, 05 Jul 2026 01:16:39 +0300Kostas Maistrelishttps://en.maistrelis.com/items/eisagogi-paragogos/<p> <p>Source (R Markdown) of the lesson «Introduction to Derivatives».</p> </p>Introduction to Derivatives — A Car on the Roadhttps://en.maistrelis.com/articles/eisagogi-paragogos/Sun, 05 Jul 2026 00:44:39 +0300Kostas Maistrelishttps://en.maistrelis.com/articles/eisagogi-paragogos/A short introduction/reminder to the concept of the derivative — the «rate of change». Each lesson opens as a standalone page (R Markdown).PostgreSQLhttps://en.maistrelis.com/items/postgresql/Sat, 04 Jul 2026 23:53:37 +0300Kostas Maistrelishttps://en.maistrelis.com/items/postgresql/ <div class="item-related"> <h3 class="item-related-head">Related entities</h3> <ul class="item-list"> <li class="item-row" data-itemtype="organization"> <a class="item-row-thumb" href="https://en.maistrelis.com/items/postgresql_greece_meetup/"> <img src="https://en.maistrelis.com/items/postgresql_greece_meetup/media/postgresql_logo1.avif" alt=""> </a> <div class="item-row-meta"> <a class="item-row-title" href="https://en.maistrelis.com/items/postgresql_greece_meetup/">Greece PostgreSQL Users Group</a> <span class="submitted">2026-06-21 · <span class="item-type">Organization</span></span> </div> </li> </ul> </div> <p> </p> <div class="item-related item-subject-of"> <h3 class="item-related-head">Related content</h3> <h4 class="term-group">Blog posts</h4> <ul class="item-list"> <li class="item-row"> <a class="item-row-thumb" href="https://en.maistrelis.com/posts/postgresql_greece_meetup_event_2/"> <img src="https://en.maistrelis.com/posts/postgresql_greece_meetup_event_2/media/1780478714792.jpeg" alt=""> </a> <div class="item-row-meta"> <a class="item-row-title" href="https://en.maistrelis.com/posts/postgresql_greece_meetup_event_2/">2nd official meetup of the Greece PostgreSQL Users Group</a> <span class="submitted">2026-06-22 · <span class="item-type item-type-section">post</span></span> </div> </li> </ul> <h4 class="term-group">Documents</h4> <ul class="item-list"> <li class="item-row" data-itemtype="document_digital"> <a class="item-row-thumb" href="https://en.maistrelis.com/items/postgresql_tree_structures/"> <img src="https://en.maistrelis.com/items/postgresql_tree_structures/media/tree-pg-pdf.png" alt=""> </a> <div class="item-row-meta"> <a class="item-row-title" href="https://en.maistrelis.com/items/postgresql_tree_structures/">PostgreSQL & Tree Structures PDF</a> <span class="submitted">2026-07-04 · <span class="item-type">Document (Digital)</span></span> </div> </li> </ul> </div> <p> </p> <p> </p> <p> </p>Greece PostgreSQL Users Group Meetup #2https://en.maistrelis.com/items/postgresql_greece_meetup_event_2/Sat, 04 Jul 2026 18:13:39 +0300Kostas Maistrelishttps://en.maistrelis.com/items/postgresql_greece_meetup_event_2/<p> <div class="callout callout--info"><p class="callout-body">See the presentation online here: <a href="https://maistrelis.com/postgresql/postgresql_tree_structures/main.html#/title-slide">PostgreSQL & Tree Structures</a></p></div> </p>PostgreSQL & Tree Structures PDFhttps://en.maistrelis.com/items/postgresql_tree_structures/Sat, 04 Jul 2026 18:13:39 +0300Kostas Maistrelishttps://en.maistrelis.com/items/postgresql_tree_structures/ <p> <div class="callout callout--info"><p class="callout-body">See the presentation online here: <a href="https://maistrelis.com/postgresql/postgresql_tree_structures/main.html#/title-slide">PostgreSQL & Tree Structures</a></p></div> </p>Photo of The Arkadiko Bridge or Kazarma Bridgehttps://en.maistrelis.com/items/photo_of_the_arkadiko_bridge_or_kazarma_bridge/Sat, 04 Jul 2026 15:14:17 +0300Kostas Maistrelishttps://en.maistrelis.com/items/photo_of_the_arkadiko_bridge_or_kazarma_bridge/Toward a Culture of Collaborative Projectshttps://en.maistrelis.com/items/gia-mia-koultoura-egxeirimaton/Sat, 04 Jul 2026 12:53:11 +0300Kostas Maistrelishttps://en.maistrelis.com/items/gia-mia-koultoura-egxeirimaton/<div class="callout callout--info"><p class="callout-body">The book is written in Greek.</p></div> <p>In this work, I explore the Culture of Meaning-Based Collaborative Projects (known by its Greek acronym, KEN) a concept that emerged from my long-term participation in a range of collaborative projects.</p> <p>My central argument is that we are not isolated subjects: our “Personal Meaning” is fundamentally shaped by the social structures and collaborative projects in which we participate.</p> <p>I propose a framework for meaning-sensitive collaborative projects—organized efforts that expand every member’s ability to participate actively in shaping the group’s core ideals, values, and beliefs.</p>Ropework Categorieshttps://en.maistrelis.com/garden/ropework/ropework_categories/Sat, 04 Jul 2026 11:18:39 +0300Kostas Maistrelishttps://en.maistrelis.com/garden/ropework/ropework_categories/<h2 id="main-categories">Main Categories</h2> <ul> <li><strong>Knots</strong> <em>(stopper, binding, loop)</em> — the basic type: the knot is tied in the rope itself, without any other object or rope.</li> <li><strong>Bends</strong> — join two rope ends to each other (e.g. sheet bend, reef knot).</li> <li><strong>Hitches</strong> — tie a rope to an object: mast, ring, post (e.g. cleat hitch).</li> <li><strong>Splices</strong> — permanent joins or terminations made by interweaving the rope’s strands; stronger than knots.</li> <li><strong>Lashings</strong> — bind spars or poles together with wrapping turns (e.g. square lashing, diagonal lashing).</li> <li><strong>Whippings & Seizings</strong> — whipping: protects a rope’s end from fraying; seizing: binds two rope sections parallel to each other.</li> <li><strong>Decorative / Fancy</strong> — decorative techniques: Turk’s head, monkey’s fist, ocean plait, etc. Often combine aesthetics and function.</li> <li><strong>Marlinespike Seamanship</strong> — the umbrella of nautical rope skill: includes knots, splices, whippings, and gear handling.</li> <li><strong>Rigging</strong> — rope systems for supporting masts and controlling sails or loads; standing and running rigging.</li> <li><strong>Climbing</strong> — rope techniques for vertical movement: anchors, rappel, belay systems.</li> <li><strong>Arboriculture</strong> — ropework for tree surgery: climbing trees, lowering branches under control.</li> <li><strong>Rope Rescue / Technical Rescue</strong> — rescue at height, confined space, cliffside; standardized techniques with certifications.</li> <li><strong>Camping / Bushcraft</strong> — tents, tarp setups, suspended shelters, camp utility knots.</li> <li><strong>Fishing</strong> — a distinct tradition with its own terminology.</li> <li><strong>Tactical / Military</strong> <em>(optional — thin category)</em> — fast-roping, rappelling, field-expedient rigging under operational conditions.</li> <li><strong>Coiling & Stowage</strong> — proper storage and uncoiling of rope; fundamental to every application.</li> <li><strong>Netting</strong> — net construction: fishing nets, cargo nets, hammocks, sports nets.</li> <li><strong>Bondage</strong> — tying a person; includes shibari/kinbaku and western bondage (see subcategories).</li> <li><strong>Pioneering / Scouting</strong> — large structures from spars and rope (towers, bridges, gateways). Overlaps with lashings but has its own tradition and competitive culture (scout competitions).</li> <li><strong>Cowboy / Western ropework</strong> — lariat, lasso, trick roping, bosal, mecate. An entirely separate tradition, with its own materials (rawhide) and braiding techniques.</li> <li><strong>Stage / Theatrical Rigging</strong> — counterweight systems, fly systems in theatres. Different from nautical rigging — its own professional school (IATSE, etc.).</li> <li><strong>Industrial Rigging / Lifting</strong> — cranes, slings, load securing. Different from sailing rigging.</li> </ul> <h2 id="secondary--related">Secondary / related</h2> <ul> <li><strong>Rope Making / Cordage</strong> — making the rope itself (twisting fibres into strands).</li> <li><strong>String figures / games</strong> — figures made with a loop of string over the fingers (e.g. cat’s cradle).</li> <li><strong>Steel wire rope</strong> — rope made of twisted wires (forming process: swaging).</li> <li><strong>Knitting</strong> (<strong>Fiber Arts</strong>, along with <strong>crochet</strong>, <strong>weaving</strong>, <strong>embroidery</strong>) — knitting yarn with a hook/needles;</li> <li><strong>Macramé</strong> (can be considered <strong>Decorative Ropework</strong>) — the decorative creation of knots in textiles.</li> </ul> <h2 id="niche-but-real">Niche but real:</h2> <ul> <li><strong>Chinese Knotting (中國結)</strong> — a huge autonomous decorative tradition. Technically a subcategory of decorative, but worth mentioning.</li> <li><strong>Surgical Knots</strong> — medical, very small scale but a codified tradition (square knot variants, surgeon’s knot).</li> <li><strong>Magic / Performance Ropework</strong> — rope tricks as a genre of conjuring (Tarbell, Pavel).</li> <li><strong>Equestrian (non-cowboy)</strong> — halters, lead ropes, fiador knots. Often within cowboy, but also autonomous.</li> </ul> <h2 id="between-art-and-science">Between art and science:</h2> <ul> <li><strong>Knot Theory</strong> — mathematical topology. Strictly speaking it is not ropework (it studies closed curves in R³), but it is often mentioned alongside. I’d characterize it as <strong>adjacent</strong>, not within.</li> </ul> <h2 id="subcategories">Subcategories</h2> <h3 id="bondage-subcategories">bondage Subcategories</h3> <ul> <li><strong>Shibari / Kinbaku (日本)</strong> — Japanese tradition, emphasis on aesthetics, symmetry, and the rigger/bunny relationship. Technically very demanding.</li> <li><strong>Western bondage</strong> — a more functional approach, less aesthetically codified.</li> </ul> <h3 id="netting-subcategories">netting Subcategories</h3> <ul> <li><strong>Fishing nets</strong> — the most classic</li> <li><strong>Cargo nets</strong> — nautical/logistics</li> <li><strong>Hammocks</strong> — netting with a structural use</li> <li><strong>Hair nets / decorative nets</strong> — overlap with decorative</li> <li><strong>Sports nets</strong> — tennis, football, etc.</li> <li><strong>Climbing nets / safety nets</strong> — overlap with rescue/climbing</li> </ul> <h3 id="plain-rigging-subcategories">plain rigging subcategories</h3> <ul> <li>plain rigging (= nautical/sailing rigging)</li> <li><strong>Standing rigging</strong> — permanent installation (shrouds, stays, backstays). In industrial there is no equivalent concept — everything is temporary/load-by-load.</li> <li><strong>Running rigging</strong> — halyards, sheets, downhauls, vangs, outhauls. Dynamic handling under load in motion, with the wind changing. Industrial rigging is basically static lifts.</li> <li><strong>Sail handling integration</strong> — reefing systems, furling, jib changes. No equivalent outside the nautical world.</li> <li><strong>Traditional standing-rigging protection techniques</strong> — worming, parceling, serving (the trio that protects rope left permanently exposed). Purely nautical, nonexistent in industrial.</li> <li><strong>Deadeyes, lanyards, hearts</strong> — old tensioning systems before turnbuckles. Still alive on classic/tall ships.</li> <li><strong>Historical / traditional depth</strong> — Age of Sail rigging is a whole body of knowledge, with books like Lever’s <em>Young Sea Officer’s Sheet Anchor</em>. Industrial rigging was codified only recently (ASME B30, OSHA).</li> </ul> <h2 id="industrial-rigging-subcategories">industrial rigging subcategories</h2> <ul> <li><strong>Working Load Limits, safety factors, certifications</strong> — maximum safe load, margin against breakage, equipment certification.</li> <li><strong>Sling angle calculations</strong> — the lifting angle multiplies the load per leg.</li> <li><strong>Crane signaling</strong> — standardized signals (hand/radio) between operator ↔ crane.</li> <li><strong>More modern materials (synthetic web slings, chain slings)</strong> — synthetic web slings instead of steel wire ropes.</li> </ul>Read Only Jokeshttps://en.maistrelis.com/garden/jokes/read_only_jokes/Sat, 04 Jul 2026 11:18:39 +0300Kostas Maistrelishttps://en.maistrelis.com/garden/jokes/read_only_jokes/<p>A small collection of jokes that, by their very nature, cannot be told out loud; they have to be <strong>read</strong>. Otherwise the ambiguity that arises from the way they are written (e.g. «10» as binary or decimal) is given away and the joke falls flat — hence “read only”.</p> <h2 id="10-kinds-of-people">10 kinds of people</h2> <p>There are <strong>10</strong> kinds of people: those who understand the binary system and those who don’t.</p> <h2 id="alien--astronaut">Alien & astronaut</h2> <p><img src="https://en.maistrelis.com/garden/jokes/read_only_jokes/media/binary_joke.jpg" alt="binary joke"> </p>The Engineering of Logic (PDF)https://en.maistrelis.com/items/engineering_of_logic_pdf/Fri, 03 Jul 2026 22:58:26 +0300Kostas Maistrelishttps://en.maistrelis.com/items/engineering_of_logic_pdf/<p>PDF version of <a href="https://en.maistrelis.com/garden/epixirima_domi/">Argument structure</a> .</p>Argumenthttps://en.maistrelis.com/items/epixeirima/Fri, 03 Jul 2026 21:49:25 +0300Kostas Maistrelishttps://en.maistrelis.com/items/epixeirima/ropeworkhttps://en.maistrelis.com/items/ropework/Fri, 03 Jul 2026 19:56:23 +0300Kostas Maistrelishttps://en.maistrelis.com/items/ropework/The Normal Distribution and its originhttps://en.maistrelis.com/articles/i-kanoniki-katanomi-kai-i-proeleysi-tis/Fri, 03 Jul 2026 19:24:59 +0300Kostas Maistrelishttps://en.maistrelis.com/articles/i-kanoniki-katanomi-kai-i-proeleysi-tis/<div style="float:right;margin:0 0 6px 10px;"><img alt="normal_distribution" width="190" src="https://en.maistrelis.com/articles/i-kanoniki-katanomi-kai-i-proeleysi-tis/media/normal_distro1.png"></div> <p>Quite a few statistics and probability textbooks with an introduction to the normal distribution have passed through my hands. They almost always started with the mathematical definition and moved on to the properties and uses of the distribution. For a long time I had not found a book that explained how this formula came about — until at some point a book called Lady Luck fell into my hands which, although old, is a very good introduction to the subject of probability, and in it I found the first clear description of how the normal distribution arises.</p>Kostas Maistrelishttps://en.maistrelis.com/items/kostas_maistrelis/Fri, 03 Jul 2026 18:11:11 +0300Kostas Maistrelishttps://en.maistrelis.com/items/kostas_maistrelis/<p> <p>I’m a programmer with a long involvement in the open-source world, mostly around Linux and PostgreSQL.<br> I take part in <a href="https://www.hellug.gr/" class="external-link">Hellug</a> and the <a href="https://en.maistrelis.com/items/postgresql_greece_meetup/">PostgreSQL Greece meetup</a> , and I’m a main contributor to <a href="https://reasonablegraph.org/" class="external-link">reasonablegraph.org</a> .<br> Here I write about whatever occupies me, with no particular plan.<br> It might be computing, statistics, or something more unexpected — epidemiology, archaeology, linguistics, ropework, archival science, social sciences, digital humanities, or mathematics. If there’s a common denominator, it’s curiosity, not any particular field.</p>Greece PostgreSQL Users Grouphttps://en.maistrelis.com/items/postgresql_greece_meetup/Fri, 03 Jul 2026 11:07:54 +0300Kostas Maistrelishttps://en.maistrelis.com/items/postgresql_greece_meetup/ <p> <p>The Greece PostgreSQL Users Group serves Athens and the wider Greek region.</p> <p>Our goal is to build a community and a network for people who work with Postgres in their daily activities.</p> </p> <h2 id="meetup">meetup</h2> <ul> <li><a href="https://www.meetup.com/greece-postgresql-users-group/">meetup.com/greece-postgresql-users-group</a></li> </ul> <h2 id="discord">Discord</h2> <ul> <li><a href="https://discord.gg/xepUAKTAAu">discord.gg/xepUAKTAAu</a></li> </ul>2nd official meetup of the Greece PostgreSQL Users Grouphttps://en.maistrelis.com/posts/postgresql_greece_meetup_event_2/Fri, 03 Jul 2026 10:16:48 +0300Kostas Maistrelishttps://en.maistrelis.com/posts/postgresql_greece_meetup_event_2/<a href="https://en.maistrelis.com/posts/postgresql_greece_meetup_event_2/" style="float:right; margin:0 0 8px 14px;"><img src="https://en.maistrelis.com/posts/postgresql_greece_meetup_event_2/media/1780478714792.jpeg" width="180"></a> On 5 June 2026 the second meetup of the <a href="https://en.maistrelis.com/items/postgresql_greece_meetup/">Greece PostgreSQL User Group</a> took place. <br><br> I had the pleasure of taking part as a speaker, presenting "PostgreSQL & Tree Structures". <br><br> You can view the presentation here: <a href="https://maistrelis.com/postgresql/postgresql_tree_structures/main.html#/title-slide">PostgreSQL & Tree Structures</a>