CprE logic gate problem, possibly unsolvable

[delta59]

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.

 

[NascentOxygen]

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

 

[delta59]

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

that is correct

 

[NascentOxygen]

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

 

[delta59]

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

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

 

[CWatters]

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.

:-)

 

[NascentOxygen]

This probably counts as a spoiler..

Not for me. Too abstruse. But thanks for the link.

I like the answer by AlexH here: http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_cs;action=display;num=1030061582