Talk:Supersingular elliptic curve

The last list item in the "Equivalent conditions" section uses a bad definition of Hasse invariant. The correct definition of Hasse invariant is: H = the differential of the Verschiebung isogeny. This yields a modular form of weight p-1 that has zeroes of order one at the supersingular points of a modular curve. If you pull back to the lambda-line (away from characteristic 2), the resulting function is equal to the polynomial in lambda described in the list entry. The bad definition carries strictly less information than the correct one, and does not work well in families.

The page has been edited to address the (justified) concern above and no longer attempts to define the Hasse invariant. — Preceding unsigned comment added by Frobitz (talk • contribs) 01:02, 26 May 2011 (UTC)

Characteristic 2
It looks like the characteristic 2 curve listed there is actually a singular one? — Preceding unsigned comment added by 2605:E000:8517:9700:30EB:BCD3:53F:BFCF (talk) 01:02, 29 June 2017 (UTC)

Table of J-invariants
I think there is an issue with the table of J-invariants at the end of the article. The reference cited does not claim that the J-invariants for 37 are the values quoted, it lists the polynomial. If that polynomial was defined over the reals, the roots would be as claimed. However, since supersingular elliptic curves must be defined over a field of positive characteristic, it doesn't make sense to solve the polynomial in R. In fact, the J-invariant for an elliptic curve over F_p is defined in F_p^2, so the polynomial in the reference should be solved mod 37^2, not on the reals.