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What A Requirement List Admits

Fifty notes on what a list of requirements admits

Halving

Every item halves what is left

A list whose items must all be met halves its own intake with each one added.

Part one

9 notes in this part

The One Convention Everything Rests On

Each item on a list is counted as a separate coin. That is a unit of measurement, not a claim about anybody, and every figure on this site depends on it.

Reference

What The First Compulsory Item Costs

The first item on a list throws away half the possibility space. It is the largest single cut any item will ever make, and it is the one nobody thinks about.

Analysis

One In Two, Four, Eight, Sixteen

The full table of compulsory-only lists, from one item to eight. Nine shapes, nine powers of two, and no exceptions anywhere in the sequence.

Reference

The Eighth Item And Where It Leaves You

Eight compulsory items admit one profile in two hundred and fifty-six. The eighth line is the one that gets argued about and the one that changes least.

Analysis

Why Lists Get Longer And Never Shorter

Adding a line costs the author nothing and costs the filter half of everything. The asymmetry is structural, and it explains how lists reach eight items.

Analysis

Why This Record Stops At Eight

Eight compulsory and eight optional items is where the enumeration ends. The bound is a choice, it is stated rather than implied, and nothing new lies past it.

Reference

Reading A List You Did Not Write

What the arithmetic lets a reader work out about a list in front of them, and the much longer list of things it does not.

Analysis