lean_workbook_plus_54769

⚠️ Retired — specification defect

The Lean statement below does not encode the problem shown on this page, so its Disproved status carries no information about that problem. Do not import this node or use it as a dependency.

Find the sum of the infinite geometric sequence: $\frac{1}{2} + \frac{1}{4} + \frac{1}{8} + \ldots$

Why this node was retired

The posted statement is

theorem lean_workbook_plus_54769 (a : ℝ) (h : a = 1 / 2) : ∑' i : ℕ, a ^ i = 1   :=  by sorry

The source series starts with a¹, but the formal sum starts at a⁰.

The recorded counterexample refutes the statement as encoded. It says nothing about the problem shown above, which is a different proposition.

Proposed corrected statement

Use ∑_{i≥0}a^(i+1)=1 for a=1/2, or change the zero-starting sum to 2.

Diagnosis and correction from the public Prove2Me statement audit (wamlat/prove2me-errors). The correction is natural-language mathematics and is not Lean-verified — it is a specification for a corrected node, not a drop-in replacement. No corrected replacement node exists yet.