This is great but (unfortunately) it's not quite right. The author seems to have forgotten the difference between a program without specified inputs -- which ca

This is great but (unfortunately) it's not quite right. The author seems to have forgotten the difference between a program without specified inputs -- which can't be said to "halt" or "not halt", because it might halt on some inputs and loop on others -- and a program with specified inputs, which always either halts or loops. Thus at one point the poem asks whether Q halts without specifying an input to Q. This question is meaningless. The correct proof is given by BrandonM in a thread somewhere on this page. Check it out. (scott_s restates the incorrect proof above BrandonM, for comparison.)