Consider a task where a language model's response is divided into segments, and each segment is classified by a human annotator. The set of possible labels is {1, -1}, where 1 represents an 'aligned' segment and -1 represents a 'misaligned' segment. An annotator reviews the second segment of a response, which contains factually incorrect information, and determines it is 'misaligned'. How would the ground truth label for this second segment be correctly represented?

In a scenario where a language model's response is broken into segments for evaluation, a human reviewer assigns a definitive label to each segment from a predefined set (e.g., {1 for 'helpful', -1 for 'unhelpful'}). This definitive, correct label for a single segment is known as the ground truth and is represented by the notation ____.