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modular-arithmetic

A research helper for solving graph number theory problems involving modular arithmetic, CRT, and Euler's theorem.

Install

mkdir -p .claude/skills/modular-arithmetic && curl -L -o skill.zip "https://agentskills.codes/api/skills/download/2680" && unzip -o skill.zip -d .claude/skills/modular-arithmetic && rm skill.zip

Installs to .claude/skills/modular-arithmetic

Activation

This is the description your AI agent reads to decide when to run this skill — the better it matches your request, the more reliably it fires.

Problem-solving strategies for modular arithmetic in graph number theory
72 charsno explicit “when” trigger
Intermediate

Key capabilities

  • Calculate modular inverses using the Extended Euclidean Algorithm
  • Solve systems of modular equations with the Chinese Remainder Theorem
  • Simplify Euler totient functions
  • Verify quadratic residues using the Legendre symbol
  • Determine the order of elements and primitive roots

How it works

The skill applies number theory strategies through symbolic computation tools like Sympy and Z3. It maps mathematical definitions to specific solver commands for verification and calculation.

Inputs & outputs

You give it
Mathematical expression or system of modular equations
You get back
Symbolic proof or numerical solution

When to use modular-arithmetic

  • Calculate modular inverses
  • Solve systems of modular equations
  • Verify quadratic residues
  • Compute Euler totient functions

About this skill

Modular Arithmetic

When to Use

Use this skill when working on modular-arithmetic problems in graph number theory.

Decision Tree

  1. Extended Euclidean Algorithm

    • Find gcd(a,b) and x,y with ax + by = gcd(a,b)
    • Modular inverse: a^{-1} mod n when gcd(a,n) = 1
    • sympy_compute.py solve "a*x == 1 mod n"
  2. Chinese Remainder Theorem

    • System x = a_i (mod m_i) with coprime m_i
    • Unique solution mod prod(m_i)
    • z3_solve.py prove "crt_solution_exists"
  3. Euler's Theorem

    • a^{phi(n)} = 1 (mod n) when gcd(a,n) = 1
    • phi(p^k) = p^{k-1}(p-1)
    • sympy_compute.py simplify "euler_phi"
  4. Quadratic Residues

    • Legendre symbol: (a/p) = a^{(p-1)/2} mod p
    • Quadratic reciprocity: (p/q)(q/p) = (-1)^{...}
    • Tonelli-Shanks for square roots
  5. Order and Primitive Roots

    • ord_n(a) = smallest k with a^k = 1 (mod n)
    • Primitive root: ord_n(a) = phi(n)

Tool Commands

Sympy_Mod_Inverse

uv run python -m runtime.harness scripts/sympy_compute.py solve "a*x == 1 mod n" --var x

Z3_Crt

uv run python -m runtime.harness scripts/z3_solve.py prove "solution_exists_iff_pairwise_coprime"

Sympy_Euler_Phi

uv run python -m runtime.harness scripts/sympy_compute.py simplify "phi(p**k) == p**(k-1)*(p-1)"

Z3_Quadratic_Residue

uv run python -m runtime.harness scripts/z3_solve.py prove "legendre_symbol_multiplicative"

Key Techniques

From indexed textbooks:

  • [Graph Theory (Graduate Texts in Mathematics (173))] By N we denote the set of natural numbers, including zero. The set Z/nZ of integers modulo n is denoted by Zn; its elements are written as i := i + nZ. When we regard Z2 = {0, 1} as a eld, we also denote it as F2 = {0, 1}.

Cognitive Tools Reference

See .claude/skills/math-mode/SKILL.md for full tool documentation.

When not to use it

  • Problems outside of graph number theory
  • General arithmetic not involving modular systems

Limitations

  • Requires specific solver scripts for execution
  • Limited to the mathematical domains defined in the decision tree

How it compares

It automates the application of number theory theorems via CLI-based symbolic solvers instead of manual derivation.

Compared to similar skills

modular-arithmetic side by side with the closest alternatives in the catalog.

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modular-arithmetic (this skill)27moReviewIntermediate
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openalex-database487moReviewIntermediate
scientific-critical-thinking187moReviewAdvanced

Try saying

Example prompts that trigger this skill in your AI assistant.

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