Is it permissible to take back one's wife after divorcing her with three pronouncements of divorce in a single utterance in court, having forgotten the judge's statement regarding the three pronouncements, and then taking her back during her 'iddah, knowing that he has been blessed with a daughter by her?

The majority of scholars hold that a triple divorce pronounced in a single utterance or in successive utterances counts as three divorces, rendering the wife irrevocably divorced (baynunah kubra). This is the relied-upon opinion. Therefore, your return to your wife is invalid, and you must separate from her immediately. As for the daughter born during this period, she is your daughter and is attributed to you. It should be noted that a judge's ruling resolves disputes in matters of ijtihad (independent legal reasoning). If the court that ruled on the divorce was a Sharia court, then you are not permitted to return to your wife unless she marries another man and he divorces her after consummating the marriage, or he dies and her waiting period (iddah) expires. In the absence of Sharia courts, Islamic centers can assume the role of Sharia judiciary.

However, Shaykh al-Islam Ibn Taymiyyah is of the opinion that a triple divorce pronounced successively before a return (raj'ah) or a new marriage contract counts as a single divorce. According to this view, your return to your wife is valid.