If you counter a spell cast for its Flashback cost from the graveyard, it gets exiled. The rule that covers flashback is 702.33a, and it says


  Flashback appears on some instants and sorceries. It represents two static abilities: one that functions while the card is in a player's graveyard and the other that functions while the card is on the stack. "Flashback [cost]" means "You may cast this card from your graveyard by paying [cost] rather than paying its mana cost" and "If the flashback cost was paid, exile this card instead of putting it anywhere else any time it would leave the stack." Casting a spell using its flashback ability follows the rules for paying alternative costs in rules 601.2b and 601.2e-g.


Countering a spell normally sends it to the graveyard (or, in some cases, exile, its owner's hand, or their library), but the flashback ability makes it go to exile instead.

It's worth noting that if a counterspell says to exile the spell it's countering (like Spelljack, for example), and then does something with it after it's exiled, that still happens. That's because if the spell is getting exiled anyway, the flashback ability doesn't change anything.

Is a countered flashback spell exiled?
What are people's views on this?  To be specific: suppose a PhD student has produced a piece of original mathematical research. Suppose that student's supervisor suggested the problem, and gave a few helpful comments, but otherwise did not contribute to the work.  Should that supervisor still be named as a co-author, or would an acknowledgment suffice?

I am interested in two aspects of this. Firstly the moral/etiquette aspect: do you consider it bad form for a student not to name their supervisor?  Or does it depend on that supervisor's input?  And secondly, the practical, career-advancing aspect: which is better, for a student to have a well-known name on his or her paper (and hence more chance of it being noticed/published), or to have a sole-authored piece of work under their belt to hopefully increase their chances of being offered a good post-doc position?

[To clarify: original question asked by MrB ]
