CprE logic gate problem, possibly unsolvable

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Discussion Overview

The discussion revolves around a logic gate problem involving three inputs (x, y, z) and a requirement to produce their negations (~x, ~y, ~z) using no more than two inverters. Participants explore the solvability of the problem and consider various approaches, including the use of other logic gates and quantum gates.

Discussion Character

  • Homework-related
  • Debate/contested
  • Exploratory

Main Points Raised

  • One participant expresses doubt about the problem's solvability after extensive attempts, particularly when all inputs are zero.
  • Another participant clarifies that while only two inverters can be used, other gates are permitted.
  • A suggestion is made to use an exclusive-OR (XOR) gate for inversion, but this is challenged as it does not resolve the original problem.
  • A link to a paper is shared, suggesting that the problem may be too complex for a PhD qualifying exam, indicating its difficulty level.
  • Another participant expresses that the linked paper is too complex for their understanding but appreciates the contribution.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the solvability of the problem, with some expressing skepticism and others proposing potential solutions that remain unverified.

Contextual Notes

The discussion highlights limitations in understanding the problem's requirements and the complexity of the proposed solutions, particularly regarding the use of XOR gates and the constraints on inverters.

delta59
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Homework Statement

I was having a casual chat with one of my professors and he presented me with a problem that after 4 hours of attempting I believe is unsolvable. the set up is pretty simple.

you have 3 inputs x,y,z that go into a system, the output is ~x,~y,~z. However you are only allowed to use 2 inverters.

I can get very close but there are a few instances where I can't get things to jive, specifically where x=0 y=0 and z=0.

Basically I want to know if this problem is solvable, I have looked into quantum gates to see if there is some way to hybrid this but my knowledge of them is limited.
 
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Other gates are allowed, but no more than 2 can be inverting?
 
NascentOxygen said:
Other gates are allowed, but no more than 2 can be inverting?

that is correct
 
So I'd just use an exclusive-OR to perform inversion. Done! :wink:
 
NascentOxygen said:
So I'd just use an exclusive-OR to perform inversion. Done! :wink:

A XOR gate is a inversion gate so I still run into the same problem how would you do this?
 
This probably counts as a spoiler..

http://www2.engr.arizona.edu/~srini/papers/Srini-Pulse-Inverter.pdf

I do not think this problem can be answered by someone in a PhD qualifying exam (say, given an entire hour for this problem alone) if that’s the first time the person is seeing the question.
:-)
 
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