Comments 29
Но можно сказать еще проще: это число всех точек на конкретной кривой + одна точка на бесконечности. Вы можете посмотреть мою предыдущую статью
Я посмотрел вашу предыдущую статью и она так же слишком переполнена словами, которые средний айтишник (к которым я отношу себя) не знает.
Группа — это множество, на котором определена некоторая обратимая ассоциативная бинарная операция. Если на пальцах, то можно сказать что группа — это когда можно умножать и делить.
Например, целые числа образуют группу по сложению, то же самое можно сказать про вещественные или рациональные числа.
Без ноля те же самые множества образуют группу по умножению.
Более подробно об этом можно почитать в Википедии
Теперь мы говорим про порядок группы. У нас есть две непрерывные гладкие функции определённые на всём множестве вещественных чисел. Будет ли порядок группы точек первой кривой отличаться от порядка группы второй кривой?
А если одна кривая определена на отрезке вещественных чисел? Например, равны ли порядки для групп точек кривой x2+y2=1 и кривой y=sin(x)?
Нет, только умножение. Если операций две — то это уже поле (или кольцо, если вторая операция необратима).
Обратите внимание также на формулировку теоремы Tate:
Две кривые над одним конечным полем изогенны тогда и только тогда, когда порядки их групп равны.
Кривая над конечным полем никак не может содержать бесконечное количество точек :-)
Ага, всё сложнее. У нас рядом с «группой» появляется слово «поле». Группа — это когда определена операция умножения, поле — когда определены умножение и сложение.
Конечное поле означает, что у нас сами кривые — это всего лишь множество точек, это не «бесконечная гладкая всюду дифференцируемая» кривая из матанализа.
Пытаюсь развернуть определение «теоремы Tate»: Кривая — конечное множество точек на поле, описываемое какой-то функцией. Для поля определены операции умножения и сложения. Для точек кривой как минимум определено умножение и деление.
Мы говорим, что две такие кривые изогенны, тогда и только тогда, когда содержат одинаковое количество точек, так?
Раскрывая определение изогенности:
Если кривые заданы над множеством точек, для которых определено умножение, деление и сложение, то тогда и только тогда, если у кривых одинаковое количество точек, то:
Существует такая функция, отображающая точки первой кривой в точки второй кривой, которая для двух любых точек первой кривой, отобразит их сумму на первой кривой в сумму отображений точек на второй кривой.
Переводя на компьютерный язык:
Если у нас есть тип данных с конечным числом значений (enum или int), для которого определены операции сложения, умножения и деления, то для любых двух одинаковых по длине массивов элементов этого типа, мы можем создать такую функцию, что она будет отображать все элементы первого массива во второй массив, причём так, что для любой пары элементов из первого массива мы сможем отобразить их в такие элементы второго массива, что сумма значений выбранной пары элементов первого массива равна сумме элементов второго массива.
У меня есть некоторое ощущение, что в районе «поля» задаются какие-то ещё ограничения, которые я не понял.
Допустим, у меня есть поле [1,2,3,4,5,6]. На этом поле у меня определены операции сложения (для некоторых элементов), умножения (аналогично), деления (аналогично).
1) Является ли 1-6 полем? Мне кажется, что нет. Если таки да, то:
Допустим, у меня есть кривая [1,2,3] и и [4,5,6]. Есть ли такое отображение, которое будет давать изогенное отображение? Как оно выглядит?
Если я где-то сделал фатальную ошибку, объясните мне её, пожалуйста. И если это возможно, проиллюстрируйте на конечном множестве чисел как оно должно быть. Спасибо.
Интересно, если у меня есть беззнаковая арифметика по модулю 256, то это будет полем?
Мне как айтишнику будет очень легко смотреть на математические операции над байтом.
Беззнаковая арифметика по модулю 256 — это не поле, а кольцо. Разница — в обратимости умножения. Например, нельзя разделить 1 на 2 нацело.
Тем не менее, с 256 элементами поле построить можно — это будет поле двоичных полиномов, порожденное полиномом 8й степени. Именно в таком поле производит вычисления, к примеру, алгоритм CRC-8 (вообще, все семейство алгоритмов CRC основано на полях двоичных полиномов, порожденных полиномами соответствующих степеней). Роль сложения в таких полях играет операция XOR (побитовое исключающее "или").
Вы не можете взять и поделить его на две одинаковые части, поскольку каждая из них по отдельности не будет полем.
Elliptic Curve defined by y^2 = x^3 + 1 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 2 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 3 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 7 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 11 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 14 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + x + 2 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + x + 5 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + x + 6 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + x + 7 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + x + 10 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + x + 11 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 2*x + 6 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 2*x + 8 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 2*x + 10 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 2*x + 12 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 2*x + 14 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 2*x + 15 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 2*x + 17 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 2*x + 18 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 3*x + 6 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 3*x + 8 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 3*x + 10 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 3*x + 12 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 3*x + 14 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 3*x + 15 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 3*x + 17 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 3*x + 18 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 4*x + 1 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 4*x + 3 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 4*x + 7 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 4*x + 9 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 4*x + 15 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 4*x + 17 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 5*x + 1 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 5*x + 4 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 5*x + 11 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 5*x + 13 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 5*x + 14 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 5*x + 16 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 6*x + 1 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 6*x + 3 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 6*x + 7 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 6*x + 9 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 6*x + 15 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 6*x + 17 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 7*x + 2 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 7*x + 5 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 7*x + 6 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 7*x + 7 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 7*x + 10 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 7*x + 11 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 8*x + 2 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 8*x + 8 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 8*x + 9 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 8*x + 12 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 8*x + 13 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 8*x + 15 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 8*x + 16 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 8*x + 18 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 9*x + 1 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 9*x + 3 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 9*x + 7 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 9*x + 9 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 9*x + 15 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 9*x + 17 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 10*x + 3 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 10*x + 4 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 10*x + 5 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 10*x + 8 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 10*x + 10 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 10*x + 12 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 10*x + 13 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 10*x + 18 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 11*x + 2 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 11*x + 5 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 11*x + 6 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 11*x + 7 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 11*x + 10 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 11*x + 11 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 12*x + 2 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 12*x + 8 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 12*x + 9 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 12*x + 12 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 12*x + 13 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 12*x + 15 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 12*x + 16 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 12*x + 18 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 13*x + 3 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 13*x + 4 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 13*x + 5 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 13*x + 8 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 13*x + 10 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 13*x + 12 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 13*x + 13 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 13*x + 18 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 14*x + 6 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 14*x + 8 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 14*x + 10 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 14*x + 12 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 14*x + 14 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 14*x + 15 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 14*x + 17 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 14*x + 18 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 15*x + 3 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 15*x + 4 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 15*x + 5 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 15*x + 8 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 15*x + 10 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 15*x + 12 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 15*x + 13 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 15*x + 18 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 16*x + 1 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 16*x + 4 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 16*x + 11 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 16*x + 13 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 16*x + 14 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 16*x + 16 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 17*x + 1 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 17*x + 4 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 17*x + 11 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 17*x + 13 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 17*x + 14 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 17*x + 16 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 18*x + 2 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 18*x + 8 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 18*x + 9 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 18*x + 12 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 18*x + 13 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 18*x + 15 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 18*x + 16 over Finite Field of size 19
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Elliptic Curve defined by y^2 = x^3 + 18*x + 18 over Finite Field of size 19
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Это не моя статья. Поля из шести элементов существовать не может, из-за того что не получается выдержать обратимость умножения.
При написании статьи всегда возникает вопрос: насколько далеко стоит уходить в описание элементарных понятий. Ведь можно сделать статью либо недоступной к пониманию, либо просто скучной. Ее главная цель — вызвать интерес к предмету, даже если что-то не совсем понятно. В любом случае большое спасибо за сигнал — я добавлю определений в первую статью.
Другими словами, если бы все понятия иллюстрировались примером на конкретных компьютерных типах данных, то это бы сильно помогло понять их.
Постквантовая реинкарнация алгоритма Диффи-Хеллмана: вероятное будущее (изогении)