alt Hacker NewsI don't know much about CSS, but Turing completeness is notorious for showing up in systems unintentionally.
It doesn't take much to be Turing-complete - if a system provides unbounded read/write memory plus branching or conditional recursion you're usually there.
As an example, Magic The Gathering (the card game) is Turing-complete: https://arxiv.org/abs/1904.09828 . You can use creature tokens as memory and various game mechanics to do flow control. Was this intentional by the designers? Most likely not...
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lproven • yesterday at 1:13 PM
> Turing completeness is notorious for showing up in systems unintentionally
Greenspun's 10th law.
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* MOV x86: using memory mapped lookup tables, you can simulate logic gates and branching using only MOV.
* PowerPoint (Without Macros): using On-Click Animations and Hyperlinks, shapes on slides act as the tape and clicking them triggers animations that move the head or change the state of the slide.
* find and mkdir (Linux Commands): find has a -execdir flag executes commands for directories it finds. By using mkdir to create specific folder structures, you can create a feedback loop that functions as a Tag System (aka universal computation).
* Soldier Crabs: Researchers showed that swarms of Mictyris guinotae can be funneled through gates to implement Boolean logic. While a full computer hasn't been built with them, the logic gates (AND, OR, NOT) are the building blocks for one.
Even water is Turing Complete:
* Fluidic Logic Gates: the Coandă effect is the tendency of a fluid jet to stay attached to a convex surface. By using tiny air or water jets to push a main stream from one channel to another, you can create the fluid equivalent of a transistor.
* MONIAC (Monetary National Income Analogue Computer)
* Navier-Stokes equations describe how fluids move are TC.
* In 2015, Stanford researchers developed a computer that operates using the physics of moving water droplets. Tiny iron-infused water droplets moved by magnetic fields through a maze of tracks. The presence or absence of a droplet represents a 1 or a 0. By colliding or diverting each other, the droplets interact perform calculations.