brain
tamnd's digital brain — notes, problems, research
43815 notes
We are asked: > How many addition chains of length $9$ have (52) as their reduced directed graph (RDG)?
We are asked to find an _addition-subtraction chain_ for some integer $n$ that has fewer steps than the minimal _addition chain_ length $l(n)$.
We are asked to **explore the problem of minimizing** f = cq + (r - q) for an addition chain
Let $(a_0,a_1,\ldots,a_r)$ be an addition chain for $n$, where $a_0=1$ and each term $a_i$ with $i>0$ is the sum of two earlier terms.
Yes, the inequality $\nu(n) \le 2^{l(n) - \lambda(n)}$ holds for all positive integers $n$.
Let $n$ be a positive integer, and recall that a **small step** in an addition chain is a step of the form $a_{i+1} = a_i + 1$.
We are asked to compute the $n$th Fibonacci number $F_n$ modulo $m$, for given large integers $n$ and $m$.
Let $y = (.d_1 d_2 \ldots d_k)_2$ be a binary fraction, where $0 < y < 1$ and each $d_j \in {0,1}$.
Let $C(n)$ denote the addition chain produced by the construction in the proof of Theorem F.
Brauer's inequality (50) asserts that, for any positive integers $a_1, a_2, \dots, a_n$ satisfying $a_1 < a_2 < \cdots < a_n$ and any addition chain of length $l$ ending at $a_n$, the following inequa...
We fix the argument by making the reuse of $F$-addition chains explicit and by separating cleanly the two sources of cost: the chain for $B$ and the chain for $n$.
The reviewer's objections are fatal.
Let $l(n)$ denote the minimum addition-chain length of $n$, and let $l^F(n)$ denote the length obtained by the factor method.
Let the multiplicity of an element $x$ in a multiset $A$ be denoted by $m_A(x)$.
We are asked to show that for any positive constant $\beta$ there exists a constant $\alpha < 2$ such that \sum \binom{m+s}{t+v} \binom{l+v}{v}^2 \binom{(m+s)^2}{t} < \alpha^m for all sufficiently lar...
In Lemma J, we are concerned with a sequence of indices or points along which a certain property holds.
Let $l^{(0)}(n)$ denote the length of the addition chain for $n$ produced by the binary S-and-X method, and let $\lambda(n)$ denote the minimal length of an addition chain for $n$.
Let s(n)=l(n)-\lambda(n),\qquad s^*(n)=l^*(n)-\lambda(n), where $\lambda(n)=\lfloor \log_2 n\rfloor$.
The reviewer is correct.
**Solution to Exercise 4.
The proposed solution does **not** answer the exercise that was asked.
Each node in the tree of Figure 15 corresponds to an integer $n \le 100$ and stores the information of which two previously computed powers were multiplied to produce $x^n$.
Let 1=a_0<a_1<\cdots<a_r=n be an addition chain for $n$, and let $l(n)$ denote the minimal length of an addition chain for $n$.
Let $T(n)$ denote the power tree defined in Exercise 5, and let $d(n)$ be the length of a shortest path from the root $1$ to the node $n$ in this tree.
There is not enough information to diagnose the algorithm from this sample alone.
**Exercise 4.
We consider each part separately.
We are asked to construct the first $r+1$ levels of the "power tree" as defined in Figure 14 and in Exercise 4.
**Exercise 4.
We are asked to compute $2^{375}$ by various exponentiation methods.
Let u(x)=u_nx^n+\cdots+u_0 be reducible over the integers, and let
We are asked to write a MIX program for Algorithm A (the right-to-left binary method for exponentiation) to compute $x^n \bmod w$, where $w$ is the word size, and then to compare it with a serial mult...
Let u(x)=u_nx^n+\cdots+u_0 be reducible over the integers, and let
Let \(u(x)\in \mathbb{Z}[x]\) be irreducible, with \(n=\deg u\) and coefficient height \(H\).
The solution addresses the exact question by formalizing the notion of "almost always" as the limit of the proportion of reducible primitive polynomials among all primitive polynomials of bounded heig...
Let $u(x) = x^n + u_{n-1}x^{n-1} + \cdots + u_1x + u_0$ be a polynomial with integer coefficients, $u_0 \ne 0$, and suppose either |u_{n-1}| > 1 + |u_{n-2}| + \cdots + |u_0| or the variant case in the...
Let $n$ be fixed and let $p \to \infty$.
The solution addresses the exact question by formalizing the notion of "almost always" as the limit of the proportion of reducible primitive polynomials among all primitive polynomials of bounded heig...
Let u(x)=\prod_{i\ge 1} u_i(x)^i,\qquad v(x)=\prod_{i\ge 1} v_i(x)^i, where each $u_i(x)$, $v_i(x)$ is squarefree and the families $\{u_i\}$, $\{v_i\}$ are pairwise coprime within themselves.
The statement is **false in general**.
For each positive integer $n$, let \Phi_n(x)=\prod_{\substack{1\le k\le n\\ \gcd(k,n)=1}}(x-\omega^k), \qquad \omega=e^{2\pi i/n}.
Let $p$ be an odd prime and $d \ge 1$.
Let R=\mathbb{F}_p[x]/(q(x)).
The solution is essentially correct and follows a standard and valid strategy for this theorem.
Let f_n(x)=a_nx^n+a_{n-1}x^{n-1}+\cdots+a_0 be a primitive polynomial of degree $n$ with integer coefficients, and let
Let $u(x)$ be a random monic polynomial of degree $n$ over $\mathbb{F}_p$.
The solution correctly addresses the exercise.
Let $u(x) = p_1(x)\cdots p_r(x)$ be squarefree, and let $\deg p_i(x) = d_i$ with $\sum_{i=1}^r d_i = n = \deg(u)$.
The solution correctly addresses the exercise.
The solution correctly addresses the exercise.
Let $u(x)$ be a polynomial with integer coefficients that is squarefree over $\mathbb{Z}$.
Let \[ u(x)=u_n x^n+\cdots+u_0=u_n\prod_{j=1}^n(x-\alpha_j), \qquad \|u\|^2=\sum_{j=0}^n |u_j|^2, \qquad
The solution correctly addresses the exercise.
The solution correctly addresses the exercise.
We are asked to reconstruct a binary string given the counts of its consecutive pairs grouped by how many ones they contain.
Let $u(x) = u_n x^n + \cdots + u_0$ be a primitive polynomial with integer coefficients, and let $v(x) = u_n^{-1} \cdot u(x / u_n) = x^n + u_{n-1} u_n^{-1} x^{n-1} + u_{n-2} u_n^{-2} x^{n-2} + \cdots...
The solution correctly addresses the exercise.
The solution correctly addresses the exercise.
We work modulo an odd prime $p$ and aim to factor x^8 + 1 \in \mathbb{F}_p[x] in terms of the radicals $\sqrt{-1}$, $\sqrt{2}$, $\sqrt{-2}$ when they exist.
The solution correctly addresses the exercise.
Let $u(x)=x^8+1.$ We seek the number $r$ of irreducible factors of $u(x)$ modulo a prime $p$.
Assume that $u(x)$ is squarefree and satisfies u(x)=p_1(x)p_2(x)\cdots p_r(x), as in (6).
We are given a black-box quantum operation that acts on a single qubit.
The issue identified in the review is not a local flaw but a complete mismatch between the question and the provided argument.
Assume that $u(x)$ is squarefree and satisfies u(x)=p_1(x)p_2(x)\cdots p_r(x), as in (6).
The solution addresses both parts of the exercise.
Assume that $u(x)$ is squarefree and satisfies u(x)=p_1(x)p_2(x)\cdots p_r(x), as in (6).
We are asked to prove the congruence x^p - x \equiv (x - 0)(x - 1) \cdots (x - (p-1)) \pmod{p}, \eqno(9) where $p$ is a prime number.
The failure is not algorithmic, it is a parsing issue caused by the fact that the solution assumes every line of input is purely numeric.
I have carefully traced the construction and identified why the previous implementation produces incorrect matrices.
Let $p$ be a prime and let $u(x)$ be a random monic polynomial of degree $n \ge 2$ over the finite field $\mathbb{F}_p$.
The solution addresses both parts of the exercise.
The solution addresses both parts of the exercise.
The exercise asks for a direct algebraic simplification of two displayed identities involving content and primitive part of polynomials over a unique factorization domain $S$.
We are asked to prove that for the sequence of polynomials $u_j(x)$ defined in equation (16) of Section 4.
Let $u_0(x),u_1(x),\dots,u_{k+1}(x)$ be the Sturm sequence generated from a real polynomial $u(x)$ of degree $m=\deg(u)$ as in (29): u_0(x) = u(x),\qquad u_1(x) = u'(x), and for $j \ge 1$,
The game is played on a tree, which is an undirected, connected, acyclic graph.
We treat the problem in two parts: first the general existence theorem for greatest common right divisors of integer matrices, then the explicit computation for the specific matrices.
We are asked to analyze **Algorithm C** for computing the greatest common divisor (gcd) of two integer polynomials of degree $n$ with coefficients bounded in absolute value by $N$, and to prove that i...
The previous write-up fails at a foundational level because it treats the task as an array-sorting problem, while the exercise is about the structure of the free associative algebra over an alphabet.
Let $A=(a_{ij})$ be an $n\times n$ real matrix, and let $r_i=(a_{i1},a_{i2},\ldots,a_{in})$ denote its $i$th row.
Let N(d_1,\ldots,d_n;S_1,\ldots,S_n) = |S_1|\cdots |S_n| -
**Corrected Solution to Exercise 4.
The reviewer feedback does not match the exercise being solved.
The solution does not correctly address the statement being proved, and it does not provide a valid argument that the pseudo-remainder must be divisible by the leading coefficient $l(v)$.
Let $S$ be a unique factorization domain, and let $S[x]$ denote the ring of polynomials in one indeterminate $x$ with coefficients in $S$.
The question refers to the row-naming convention of Table 1 in §4.
Let $f(x)$ be a polynomial with integer coefficients, and suppose that $f(x)$ is irreducible over the domain of integers.
Let $f(x)$ be a unit in the polynomial ring over a unique factorization domain $S$.
**Solution to Exercise 4.
Let $S = \mathbb{F}_p$.
We are asked whether the _binary gcd algorithm_ (Algorithm 4.
**Problem 2.
Let $F=\mathbf F_p$.
We are asked to compute the pseudo-quotient $q(x)$ and pseudo-remainder $r(x)$ over the integers for u(x) = x^6 + x^5 - x^4 + 2x^3 + 3x^2 - x + 2, \qquad v(x) = 2x^2 + 2x^2 - x + 3.
We are asked to recover a literary quotation x = x_1 x_2 represented in ASCII, from the ciphertext
**Exercise 4.
Let G=\langle a\rangle=(\mathbb Z/p\mathbb Z)^\times, where $p$ is prime and $a$ is a primitive root modulo $p$.
We are asked to solve the congruence x^2 - ay^2 \equiv b \pmod{n} for integers $x$ and $y$, given that $a, b \perp n$ and $n$ is odd, without knowledge of the factorization of $n$.
**Corrected Solution to Exercise 4.