# Homework Help: CprE logic gate problem, possibly unsolvable

1. Nov 8, 2012

### delta59

1. The problem statement, all variables and given/known data

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 cant 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.

2. Nov 9, 2012

### Staff: Mentor

Other gates are allowed, but no more than 2 can be inverting?

3. Nov 10, 2012

### delta59

that is correct

4. Nov 10, 2012

### Staff: Mentor

So I'd just use an exclusive-OR to perform inversion. Done!

5. Nov 10, 2012

### delta59

A XOR gate is a inversion gate so I still run into the same problem how would you do this?

6. Nov 12, 2012

### CWatters

This probably counts as a spoiler..

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

:-)

Last edited by a moderator: May 6, 2017
7. Nov 17, 2012