Portrait Diptych of Dürer's Parents Portrait Diptych of Dürer's Parents Portrait Diptych of Dürer's Parents (or Dürer's Parents with Rosaries) is the collective name for two late-15th century portrait panels by the German painter and printmaker Albrecht Dürer. They show the artist's parents, Barbara Holper (c. 1451–1514) and Albrecht Dürer the Elder (c. 1427–1502), when she was around 39 and he was 63 years. The portraits are unflinching records of the physical and emotional effects of ageing. The Dürer family was close and Dürer may have intended the panels either to display his skill to his parents or as keepsakes while he travelled soon after
Hinged dissection Hinged dissection A hinged dissection, also known as a swing-hinged dissection or Dudeney dissection, is a kind of geometric dissection in which all of the pieces are connected into a chain by "hinged" points, such that the rearrangement from one figure to another can be carried out by swinging the chain continuously, without severing any of the connections. Typically, it is assumed that the pieces are allowed to overlap in the folding and unfolding process; this is sometimes called the "wobbly-hinged" model of hinged dissection. The concept of hinged dissections was popularised by the author of mathematical puzzles, Henry Dudeney.