Alphabeta Math
TheoremStatement: Literature-sourcedProof: AI-generatedprecheck passaudited 2026-08-01
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The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.

  • Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
  • AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
  • AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.

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The general Leibniz rule for the n-th derivative of a product

Statement

If n∈N and f,g are n-times differentiable on an interval I, then (fg)(n)=∑j=0nι ⁣(nj) f(j)g(n−j).

Facts & Assumptions

Proof

technique · induction
1.1baseL2

For n=0, the displayed sum is ι(00)f(0)g(0)=fg=(fg)(0).

1.2ihassume-hyp

Assume the formula holds at an index k, and assume f,g have derivatives through order k+1.

2.1step 1.2L1L3

Differentiating the finite sum gives (fg)(k+1)=∑j=0kι(kj)(f(j+1)g(k−j)+f(j)g(k−j+1)).

3.1step 2.1L2L3algebra

Shift j+1 in the first sum, retain j in the second, and combine the two interior coefficients by Pascal's rule; the two boundary coefficients are 1. The result is (fg)(k+1)=∑j=0k+1ι(k+1j)f(j)g(k+1−j).

4.1step 1.1step 3.1discharge-induction∎

Thus the formula holds for every n∈N.

Depends on

Dependency tree · 2 levels

Sources