Matir (Untying a Knot) - Breaking Down the 39 Melachot

undo the knots to allow your child to keep playing  yo-yo? Also, let's say you're trying to tie your   shoes and accidentally you tie a double knot  instead of making bows. Are you allowed to undo   that knot and retie your shoe properly? One of the  melachot of Shabbat is the melacha of matir, which   means undoing a knot. Now, undoing a knot only  applies to knots that were made in a permanent way   or an expert way. But since these knots were made  accidentally, there is no problem to undo the knot   in the yo-yo string that was made accidentally or  the knot on the shoe that was made accidentally.