/**
 * Return true when intervals `[aStart, aEnd]` and `[bStart, bEnd]` share at least one instant.
 *
 * - Compares numeric Unix epoch values directly.
 * - Adjacent intervals (e.g. `aEnd === bStart`) do NOT overlap — returns `false`.
 * - Returns `false` if either interval is invalid (`start > end`).
 * - Returns `false` on invalid input (non-numeric types, non-finite values).
 *
 * @param aStart Unix epoch value (seconds or milliseconds) — first interval start
 * @param aEnd Unix epoch value (seconds or milliseconds) — first interval end
 * @param bStart Unix epoch value (seconds or milliseconds) — second interval start
 * @param bEnd Unix epoch value (seconds or milliseconds) — second interval end
 * @returns true if intervals overlap, or false on invalid input
 *
 * @example intervalsOverlapUnix(0, 1700000000, 1000000, 2000000) // true
 * @example intervalsOverlapUnix(0, 1000000, 1000000, 2000000) // false (adjacent)
 * @example intervalsOverlapUnix(0, 1000000, 1000001, 2000000) // false (disjoint)
 * @example intervalsOverlapUnix(NaN, 1700000000, 1000000, 2000000) // false
 * @example intervalsOverlapUnix("0", "1700000000", "1000000", "2000000") // true
 */
export declare function intervalsOverlapUnix(aStart: number | string, aEnd: number | string, bStart: number | string, bEnd: number | string): boolean;