RE: Post making contest
05-31-2016, 06:05 PM
This is update #76.
This specimen solution set does a remarkably good job of not actually answering the question I wanted to check my solution for. Like, sure, you've explained how to find the envelope and the very obvious point at which the Jacobian is first zero, but you haven't then actually found the domain of definition because only half of the characteristics are cut short by J=0 - those for 0 < s < 1/2 still make it to the intersection point! This presumably means that the domain of definition will be bounded by the curve along which the 1/2 < s < 1 set of characteristics hit J=0, which I've found but don't particularly like the look of, so its absence from the document specifically written to answer all the questions posed by this paper is incredibly irksome. The rest of the question was fine, though, so whatever, it looks like most of the marks for that part were for the earlier bit...
...I should eat dinner.
End of message.
This specimen solution set does a remarkably good job of not actually answering the question I wanted to check my solution for. Like, sure, you've explained how to find the envelope and the very obvious point at which the Jacobian is first zero, but you haven't then actually found the domain of definition because only half of the characteristics are cut short by J=0 - those for 0 < s < 1/2 still make it to the intersection point! This presumably means that the domain of definition will be bounded by the curve along which the 1/2 < s < 1 set of characteristics hit J=0, which I've found but don't particularly like the look of, so its absence from the document specifically written to answer all the questions posed by this paper is incredibly irksome. The rest of the question was fine, though, so whatever, it looks like most of the marks for that part were for the earlier bit...
...I should eat dinner.
End of message.