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Questions tagged [turing-completeness]

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Weaker, but similar conditions to Turing completeness?

A model of computation is called Turing complete if it can simulate any Turing machine. This rules out for example a combinational logic circuit. However, there is a sense in which combinational ...
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1answer
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Is this system Turing complete?

I want to develop a genetic program that can solve generic problems like surviving in a computer game. Since this is for fun/education I do not want to use existing libraries. I came up with the ...
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1answer
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What is the simplest/smallest subset an OOP language like C#/JavaScript that is Turing-complete?

This question is not meant to be too theoretical or nitpicky. I have experience programming, so I'm trying to get a better understanding of what it takes to get Turing-completeness by using my ...
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1answer
110 views

Can PDA model Turing Complete objects if the objects' state are finite?

I am currently reading the extended Version of the Paper Online Detection of Effectively Callback Free Objects with Applications of Smart Contract. I am trying to understand the proofs of Chapter 6. ...
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Why does Turing Tumble need gear bits to be turing complete?

I understand intuitively that gear bits in the massively successful Turing Tumble game (funded by kickstarter) are necessary for Turing completeness*. I had a fantasy about building a computer with ...
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1answer
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Obtain all possible Turing Machines from a Universal Turing Machine

Knowing how a Universal Turing Machines works and its capabilities, is it possible to obtain the collection M = {M0 , M1 , M2 , M3, … } of all possible Turing Machines? If so, can we prove that a ...
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2answers
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How can a 64KiB computer do the same task as a modern computer?

I took an extremely interesting intro to CE course, learning about transistors/memory/logic gates up to LC-3 assembly. Something that was really interesting to me was learning about how a processor's ...
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57 views

Transport Triggered CPU Architecture MOV and Turing Completeness

Reading up on TTA CPU designs and the wikipedia article states that Some TTA implementations support conditional execution. The trick to make an TTA ISA Turing-complete with an unconditional MOV ...
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Can logistic map iteration be Turing complete?

Reading that simple cellular automata like rule 110 are Turing Complete, and comparing it to some "chaotic" iterations of the logistic map where numbers are in binary form. It seems the iterations ...
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1answer
36 views

How to compute (x MOD y) with just SUM and MULT gates?

It is known that $\{ SUM, MULT \}$ is Turing-complete, i.e. every Turing machine has an equivalent circuit made up of $SUM$ and $MULT$ gates. By the way, I could not come up with designing $MOD$ ...
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7answers
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Are all turing complete languages interchangeable

Note, while I know how to program, I'm quite a beginner at CS theory. According to this answer Turing completeness is an abstract concept of computability. If a language is Turing complete, then ...
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Is it possible to have a code which cannot be solved by computer

I was looking at Turing machines and Turing completeness and I was wondering whether it is possible to prove that there is a problem which cannot be solved by a Turing complete computer or whether it ...
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1answer
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Emergent complexity and Turing Completeness

Is there some link between the concept of emergence and Turing Completeness? The ideas feel intuitively like they might be linked, but I can find nothing online. The idea came to me because I was ...
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0answers
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In what sense can a cellular automaton be Turing complete? [duplicate]

The rule 110 cellular automaton is known (or claimed) to be Turing complete. But what exactly does it mean? I do know what Turing completeness mean. Roughly speaking a language is Turing complete if ...
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1answer
126 views

Infinite Boolean circuits as a model of computation

Boolean circuits are non-uniform models of computation in that they require a different circuit for each length of input. The typical way of uniformizing a family of Boolean circuits is to define a ...
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1answer
2k views

How is PowerPoint Turing complete?

From my understanding, Turing complete means that the program or machine can complete any computation that a Turing machine can complete, which to me means any computation. So how can something like ...
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1answer
429 views

What was the first Turing-Complete programming language?

What was the first turing-complete language? Know about the first machines and computers, but not the programming language.
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1answer
191 views

Is there a dual concept to “Turing Complete” in logic?

Two computing models can be shown to be co complete if each can encode a universal simulator for the other. Two logics can be shown to be co complete if an encoding of the rules of inferences (and ...
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1answer
119 views

Who was the first to show that there is a Universal Turing-Machine that uses a binary alphabet?

The title says it all, I think. We know there are universal Turing-machines that only use a binary alphabet. But who proved this first? Turing himself showed the existence of a universal Turing ...
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3answers
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Is the ability to do depth first search a proof of Turing Completeness? Can we write a non-TC automaton that does DFS?

As the title states. Let's say we have a set of inputs that define a tree structure. Is it possible to construct an automaton that can perform depth-first search on this data that is not Turing-...
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1answer
677 views

Turing-completeness, Conway's Game of Life and Logical Gates

I was recently given an assignment at university asking me to discuss the universal computational capability of Conway's Game of Life. I'm not required to actually build up a Universal Turing machine ...
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1answer
89 views

Is there a problem solution which, if implementable in a given language, implies that that language is Turing complete?

I have been researching a bit lately and found myself thinking about the title question for some time now, but have found nothing conclusive. For example, some problems require loops practically - ...
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What portion of all possible turing machines halt?

Has anyone estimated Chaitin's constant for Turing machines with an empty tape as input?
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Is a reduced Wang B-machine Turing-complete?

A Wang B-machine has only 4 instructions: right: Move tape head right left: Move tape head left ...
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1answer
127 views

Find the odd shortest path is NL

OddPath be a set of all G, s, t, such that G is a directed graph with a path from node s to node t, and the shortest such path has odd number of edges. How can I show OddPath is NL? I think about it ...
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1answer
191 views

Lambda Calculus in Rewriting systems

How to do or implement Lambda Calculus in a Rewriting systems? Rewriting systems are Turing complete. But I can't figure out how to do lambda calculus or functions with them.
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1answer
164 views

How many gates until Turing Complete

A computer can be pretty much made using just nand gates and a clock. Suppose you randomly place down nand gates on a board and connect them randomly to other nand gates. How many gates does someone ...
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5answers
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What does being Turing complete mean?

I see that most definitions of what it is to be Turing-complete are tautological to a degree. For example if you Google "what does being Turing complete mean", you get: A computer is Turing ...
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2answers
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Looping and branching with Algorithmic Differentiation

Algorithmic (aka Automatic) Differentiation is a wonderful technique for numerical computation of derivatives. I understand how it relates to the fact that we know how to deal with every elementary ...
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1answer
53 views

Is learned RNN still universal?

I know it has been shown that RNNs are Turing complete. So for any Turing machine, there exists a configuration of a RNN that is equivalent to it. But I'm wondering, is all those configuration ...
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1answer
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Confused between turing-completeness and universal approximation - are they related?

I am trying to de-knot a point of confusion in my mind regarding "turing-completeness" and the "universal approximation theorem". The context here is deep neural nets: So, consider two types of ...
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1answer
58 views

How does universal calculator work?

As I understand, the concept 'computation' started dependent on hardware (like looms for instance). The Hardware defines (physical cascades) what happens between input and output. I think I saw in ...
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2answers
59 views

Trying to figure out if a modern computer is capable of manipulating arbitrarily large pointers

I was just thinking about Turing-completeness and its relationship with modern computers. I've always thought that a real computer is not technically Turing-complete. It is equivalent to a linear-...
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1answer
26 views

Characterisation of Turing completeness? [duplicate]

I know the definition of a Turing machine but I am trying to find a practical way to characterize a Turing-complete language. For example, an imperative language is Turing complete if it has ...
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1answer
147 views

Is Functional Complete means Turing Complete?

I noticed that AND, OR, NOT those three logic gates are Functionally Complete, it means I can represent any trues table only by those three gates. A Turing machine may halt or not in a particular ...
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1answer
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Why is the video game Braid Turing-complete?

It's written in wikipedia https://en.wikipedia.org/wiki/Turing_completeness#Games that the video game Braid is Turing-complete. I've played Braid before but I can hardly reconcile it with Turing ...
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3answers
879 views

How can a stack-based VM be Turing-Complete?

I was trying to implement a stack-based Virtual Machine (e.g. like JVM or some early version of Lua) for some benchmarks in order to test its performance against a Register-based VM. I originally ...
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9answers
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Why are some programming languages Turing complete but lack some abilities of other languages?

I came across an odd problem when writing an interpreter that (should) hooks to external programs/functions: Functions in 'C' and 'C++' can't hook variadic functions, e.g. I can't make a function that ...
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2answers
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Is there a way to test “Turing completeness”?

I asked my algorithms teacher today the very same question that is stated in the title, but he seemed a bit unsure, either on the question or on the concept, so I thought I'd try here too. Is there a ...
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2answers
43 views

Is a physical process with unbounded input Turing equivalent?

Church-Turing thesis states that any effectively computable process is computable by a TM. Let's assume for now that it means that every physical machine is computable by a TM. Let's call it A. Now ...
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3answers
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Can every self-modifying algorithm be modelled by a non-selfmodifying algorithm?

If we have any arbitrary computer program that can modify its instructions, is it possible to simulate that program with a program that cannot modify its instructions? Edit: I am new to ...
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6answers
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Is C actually Turing-complete?

I was trying to explain to someone that C is Turing-complete, and realized that I don't actually know if it is, indeed, technically Turing-complete. (C as in the abstract semantics, not as in an ...
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1answer
3k views

Can the human brain be considered Turing complete? [duplicate]

I'm not a student in computer science, but from what I understand from the Wikipedia article on the topic, a programming language is Turing complete if it can emulate another Turing complete language'...
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1answer
81 views

Turing Completeness of System Which Randomly Fails to Complete Calculations

If one were to create a variant of a turing complete language which upon completing a calculation randomly changes the answer by one, would it be Turing complete? For example, say I had a Python ...
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1answer
166 views

Is the system of measuring length in the US is Turing complete?

The author here writes: Little known fact, the system of measuring length in the US is Turing complete My question is: Is the system of measuring length in the US is Turing complete?
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Does Turing Completeness imply the existence of a Universal Program?

Please correct me if at any time my definitions are wrong. Suppose we have a programming language $L$ over some set $D$ with semantic (partial) n-ary functions $\varphi^n:D \to (D^n \to D)$. Assume $L ...
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Why does using an encoding trick like Gödel numbers make a register machine universal?

Here the author describes the Random Access Stored Program machine and the problem of indirect addressing. The author states: But this does not solve the problem (unless one resorts to Gödel ...
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2answers
544 views

Can one consider living (biological) cell to be Turing Complete?

Universal Turing Machine can be boiled down to two components. Infinite tape of input and an action table, a finite state machine that moves read/write head along the tape and writes to it depending ...
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Turing-Complete Supervised Learning Algorithms

I'm trying to decide on what algorithm I should use for my machine learning project. I need Turing-completeness. What supervised learning algorithms are Turing-complete? Of those, what are the best? ...
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Are Random Forests Turing-Complete?

Is the random forests algorithm Turing-complete? As in, can any algorithm be represented by a given "tree" in the forest?