• Our description of the DHJ theorem was confused (7 May, p 10). It should have stated: “Imagine colouring in squares in a grid. What percentage can you colour before you are forced to make a straight line along a row, column or diagonal? The DHJ theorem says the percentage decreases in cubic grids, and in higher-dimensional grids the percentage goes to zero as almost any square you colour will result in a line.”
• Our tribute to the late artist James Acord should have quoted Mark Ramsay (30 April, p 48).
• In “Uncertainty entangled”, the National University of Singapore researcher quoted was Stephanie Wehner (30 April, p 28).
