sort: clarify Less doc

clarifies the requirements for Less

Fixes #73420

Change-Id: I7d49b10fad78c618d946b3bb161ce19680ede47a
GitHub-Last-Rev: 7a49ad8
GitHub-Pull-Request: #74333
Reviewed-on: https://go-review.googlesource.com/c/go/+/683275
Reviewed-by: Keith Randall <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Auto-Submit: Keith Randall <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: jagprog5

src/sort/sort.go

@@ -26,13 +26,15 @@ type Interface interface {
 	// Sort may place equal elements in any order in the final result,
 	// while Stable preserves the original input order of equal elements.
 	//
-	// Less must describe a transitive ordering:
+	// Less must describe a [Strict Weak Ordering]. For example:
 	//  - if both Less(i, j) and Less(j, k) are true, then Less(i, k) must be true as well.
 	//  - if both Less(i, j) and Less(j, k) are false, then Less(i, k) must be false as well.
 	//
 	// Note that floating-point comparison (the < operator on float32 or float64 values)
-	// is not a transitive ordering when not-a-number (NaN) values are involved.
+	// is not a strict weak ordering when not-a-number (NaN) values are involved.
 	// See Float64Slice.Less for a correct implementation for floating-point values.
+	//
+	// [Strict Weak Ordering]: https://en.wikipedia.org/wiki/Weak_ordering#Strict_weak_orderings
 	Less(i, j int) bool
 
 	// Swap swaps the elements with indexes i and j.