Formal Methods and Z doggerel

Lemma tree very pretty
And the lemmas are all true.
But the proof of the last lemma
Is impossible to do.

Summer 1994

A pedantic grammarian once said
"Here's a great spec language called Z.
   But it's from Britain, you see,
   So please don't call it 'zee',
A name up with which I am fed.

My referee said, "Make a correction,
Or your paper will get a rejection.
  It turns me quite pale
  Seeing two heads, ribs, one tail.
So please get rid of that finite bijection."         >-||->>

for ZUM, Limerick, Summer 1995