# Questions tagged [computation-models]

The definition of the set of allowable operations used for computation and their respective costs. Some examples of models include Turing machines, recursive functions, lambda calculus, and production systems.

490 questions
Filter by
Sorted by
Tagged with
23 views

### Create a Turing machine for this interactive game

Given two players $A, B$ and some natural number $n \ge 2$, let $\#(A,B,n)$ denote the following algorithm: $A$ thinks of some number $a \in \{1,\ldots,n\}$ Until the game ends: $B$ thinks of some ...
1 vote
86 views

### Time Complexity of Exponentiation Operation as per RAM Model of Computation

Now, $\color{blue}{\text{Exponentiation}}$ is defined as Exponentiation is a mathematical operation, written as $b^n$, involving two numbers, the base $b$ and the exponent or power $n$, and ...
11k views

### Is there anything that MUST be done on a multi-core CPU?

When considering how multi-thread-friendly our program must be, my team puzzled about whether there's anything that absolutely cannot be done on a single-core CPU. I posited that graphics processing ...
19 views

### Transition System vs State Machines

Why there is no final state for a transition system? And why do NFA and DFA have final states? The transition system may or may not have any terminal states, but NFA/DFA has at least one final state (...
34 views

### Belt-based mechanical computers

I've seen a lot of mechanical computers based on gears and rigid rods, but none so far that consequently use belts (not chains) for transmission of information. Belts allow for easy negation (by ...
50 views

### If A is reducible to B, assuming A is hard, why can't "B is easy" update our belief to A is easy?

The concept of reducibility in computability theory is very confusing for me. For example, as described in Micheal Sipser's Introduction to the theory of computation, I understand that if language A ...
20 views

### Is it correct to perform feature distillation when both the teacher and student model architectures are completely different

When the architectures of the teacher and student networks do not just vary by network depths but are completely different, is it logically correct to distill knowledge at feature level (say from ...
1 vote
38 views

2k views

### Can any known sub-Turing-complete model of computation enumerate precisely the set of prime numbers?

I wish there were more, but the subject pretty much captures my whole question. Is there a non-Turing-complete model (some constrained term rewriting system or automaton or what have you) which is ...
50 views

### Differences between a computation model and an abstract data type

I am wondering about the difference between an abstract data type (ADT) and a computation model. As I understand them: A computation model defines the basic unit of computation, that is, what can be ...
6k views

### Why do pushdown automata use a stack?

I'm taking a computer theory class and my professor told us that a pushdown automaton cannot use data structures other than a stack (like a queue or multiple stacks). Why is that?
1 vote
85 views

### Is it reasonable to assume modern computers can do hardware math with integers up to 2^64?

I was writing up an algorithm that involved knowing the size of integers my hardware can manage without having to resort to software implementations of math operations and the additional computational ...
41 views

### In search for a complete definition for write-only TMs / Tapes

In the following lines I will present my question, whose content is divided in two parts: Preparation and Actual . (1) — Preparation Regarding the formal definition of the (one tape) general Turing ...
1 vote
54 views

### Confused about the concept of deciding in nondeterministic Turing machines

I read this discussion before. However i’m still confused. I used to think a language decided by a NTM if for every input $w$ in $\Sigma^*$, all of the branches in computation tree leads to a halting ...
26 views

### Why do we promote Ubiquitous Computing when there are problems out there that cannot be solved computationally?

According to Alan Turing, there are 2 types of problems i.e. NP Complete and non-NP Complete, then why do we promote Ubiquitous Computing and introducing sensors and embedded systems into our daily ...
2k views

### What is the difference between quantum computing and parallel computing?

Quantum computing essentially relies on the fact that qubits maintain multiple possible states simultaneously. Parallel computing too processes multiple states simultaneously. So what is the ...
42 views

### Is there a non PSPACE language s.t exponential padding of it is PSPACE?

I've had an exam in computational models a few days ago, and would like to check whether I made a mistake. The question goes like that: Is there a language $L \notin PSPACE$ over the alphabet {0,1} ...
50 views

### Are there infinitely many distinct implementations of any algorithm using any Turing-complete computational model?

Subject pretty much says it all. My strong impression is that for any algorithm and any choice of programming language or computational model, if it's Turing-complete, then there must be infinitely ...
711 views

### λ-Calculus extensions: meaning of extension symbols

When working with λ-Calculus I see lots of extensions that use other symbols such as ∀ <:Top {} ←, which are from "Types and Programming Languages" (WorldCat) by Benjamin C. Pierce. ...
1 vote
58 views

### Does multiplying word size numbers take constant time?

Does multiplying word size numbers (using standard grade school algorithm) take constant time? Can you use this to speed up computation and do the fast multiplication algorithms use this? By constant ...
1 vote
52 views

### Efficient comparison, using only sum, product, difference, and conditional jump if zero

I was wondering how small we could make the instruction set of a typical machine that supports a single datatype: arbitrary integers. If you need a heap, you declare an integer variable $h$ where you ...
22 views

### Is a computational model that can instantly access any storage address and can access any arbitrary number of them at once more powerful then a TM?

This would be a computational model that would have unbounded space. But with a jump command that can access and do operations on any finite number of cells at once. Actual calculations would take ...