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The main question of the PI has been beautifully answered by Moret-Bailly, but not the secondary question arisen from his expectation: "I would expect that it should be possible to write down a power series in two variables f(x,y) so that ℂ[[x,y]]/f(x,y) is non-algebraic." though we got quite close in comments.

So for the record: this is not possible. Indeed, such a singularity would be analytic by Angelo's answer to [this MO question][1] (that is by a result of Michael Artin akin to ( "On the one I mentionedsolutions of analytic equations", Invent. Math. 5 1968, 277–291, cf. Angelo's answer to http://mathoverflow.net/questions/51530/analytic-vs-formal-vs-etale-singularities) and then algebraic by Ulrich's comment (that is by Corollary 7.7.3 of the book by Casas-Alvero "Singularities of plane curves", London Mathematical Society Lecture Note Series, 278).

This is of course consistent with the fact that the example quoted by Moret-Bailly is in three variables.
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The main question of the PI has been beautifully answered by Moret-Bailly, but not the secondary question arisen from its his expectation: "I would expect that it should be possible to write down a power series in two variables f(x,y) so that ℂ[[x,y]]/f(x,y) is non-algebraic." though we got quite close in comments.

So for the record: this is not possible. Indeed, such a singularity would be analytic by Angelo's answer to [this MO question][1] (that is by a result of Michael Artin akin to the one I mentioned) and then algebraic by Ulrich's comment (that is by Corollary 7.7.3 of the book by Casas-Alvero "Singularities of plane curves", London Mathematical Society Lecture Note Series, 278).

This is of course consistent with the fact that the example quoted by Moret-Bailly is in three variables.
show/hide this revision's text 1

The main question of the PI has been beautifully answered by Moret-Bailly, but not the secondary question arisen from its expectation: "I would expect that it should be possible to write down a power series in two variables f(x,y) so that ℂ[[x,y]]/f(x,y) is non-algebraic." though we got quite close in comments.

So for the record: this is not possible. Indeed, such a singularity would be analytic by Angelo's answer to [this MO question][1] (that is by a result of Michael Artin akin to the one I mentioned) and then algebraic by Ulrich's comment (that is by Corollary 7.7.3 of the book by Casas-Alvero "Singularities of plane curves", London Mathematical Society Lecture Note Series, 278).

This is of course consistent with the fact that the example quoted by Moret-Bailly is in three variables.