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Arithmetic geometry and elliptic curves

Arithmetic geometry and elliptic curves

Warm-upHuman

On E:y2=x3+1E: y^2 = x^3 + 1 the point P=(2,3)P = (2, 3) has order 66, and 2P=(0,1)2P = (0, 1). What is the order of the point (0,1)(0, 1)?

Arithmetic geometry and elliptic curves

CoreHuman

Count the points of E:y2=x3+2E: y^2 = x^3 + 2 over F7\mathbb{F}_7, including the point at infinity. (The non-zero squares mod 77 are 1,2,41, 2, 4.)

Arithmetic geometry and elliptic curves

CoreHuman

For E:y2=x3+x+1E: y^2 = x^3 + x + 1 over F5\mathbb{F}_5 we found #E(F5)=9\#E(\mathbb{F}_5) = 9, so a=5+1−9=−3a = 5 + 1 - 9 = -3. Use #E(Fqn)=qn+1−αn−βn\#E(\mathbb{F}_{q^n}) = q^n + 1 - \alpha^n - \beta^n, where α,β\alpha, \beta are the roots of T2−aT+qT^2 - aT + q, to find #E(F25)\#E(\mathbb{F}_{25}).

Arithmetic geometry and elliptic curves

CoreHuman

Let E:y2=x3+1E: y^2 = x^3 + 1, so a=0a = 0, b=1b = 1 and 4a3+27b2=274a^3 + 27b^2 = 27. By the Nagell–Lutz theorem, a torsion point (x,y)≠O(x, y) \neq O has integer coordinates with y=0y = 0 or y2∣27y^2 \mid 27. List every integer yy that is allowed.

Write elements separated by commas. Order and repeats don’t matter — just like in a set!

Arithmetic geometry and elliptic curves

CoreHuman

In the proof of Hasse's theorem we showed m2−a mn+q n2=deg⁡(m−nϕ)≥0m^2 - a\,mn + q\,n^2 = \deg(m - n\phi) \ge 0 for all integers m,nm, n, and concluded a2≤4qa^2 \le 4q. Which justification of the last step is correct?

Choose one

Arithmetic geometry and elliptic curves

StretchHuman

Let E:y2=x3−2E: y^2 = x^3 - 2. For which fields KK is E(K)E(K) not finitely generated? (Choose all that apply.)

Choose all that apply

Arithmetic geometry and elliptic curves

CoreFormal

The lesson's Lean theorem chord_third_point has hypotheses h₁ : y₁ ^ 2 = x₁ ^ 3 + a * x₁ + b, h₂ : y₂ ^ 2 = x₂ ^ 3 + a * x₂ + b, hx : x₁ ≠ x₂ and hℓ : y₂ - y₁ = ℓ * (x₂ - x₁). What would go wrong if we deleted hx?

Choose one

Arithmetic geometry and elliptic curves

CoreComputational

Write count_points(p, a, b) returning #E(Fp)\#E(\mathbb{F}_p) for y2=x3+ax+by^2 = x^3 + ax + b over Fp\mathbb{F}_p (pp an odd prime), including the point at infinity. Then use it to check the Hasse bound for every curve over Fp\mathbb{F}_p, p<50p \lt 50.

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Arithmetic geometry and elliptic curves

StretchHuman

Which of these statements about elliptic curves EE over Q\Q are proved theorems (as of this lesson)? Choose all that apply.

Choose all that apply