Counting Foundations

Combinations Choose Two

List unordered pairs in lexicographic order. This is a small deterministic example, not solver engineering.

combinatorics-search Every row is intentionally ordered and pinned to the lesson specification.

Example

List unordered pairs in lexicographic order.

highlighted = computed this step

Step 1 — Items

Set up the exact small combinatorics values.

items, choose((A, B, C, D), 2)\begin{array}{c|c}\text{items, choose}&\text{((A, B, C, D), 2)}\end{array}

Step 2 — Combination

Compute the highlighted combinatorics value.

combination(A, B)\begin{array}{c|c}\text{combination}&\hlmath{\text{(A, B)}}\end{array}

Step 3 — Combination

Compute the highlighted combinatorics value.

combination(A, C)\begin{array}{c|c}\text{combination}&\hlmath{\text{(A, C)}}\end{array}

Step 4 — Combination

Compute the highlighted combinatorics value.

combination(A, D)\begin{array}{c|c}\text{combination}&\hlmath{\text{(A, D)}}\end{array}

Step 5 — Combination

Compute the highlighted combinatorics value.

combination(B, C)\begin{array}{c|c}\text{combination}&\hlmath{\text{(B, C)}}\end{array}

Step 6 — Combination

Compute the highlighted combinatorics value.

combination(B, D)\begin{array}{c|c}\text{combination}&\hlmath{\text{(B, D)}}\end{array}

Step 7 — Combination

Compute the highlighted combinatorics value.

combination(C, D)\begin{array}{c|c}\text{combination}&\hlmath{\text{(C, D)}}\end{array}