Winged altarpiece Winged altarpiece A winged altarpiece (also "folding altar") or winged retable is a special form of altarpiece (reredos, occasionally retable), common in Central Europe, in which the fixed shrine or "corpus" can be enclosed by two (triptych), four (pentaptych) or more (polyptych) movable wings. The technical terms are derived from : "trís" or "triple"; πέντε: "pénte" or "five"; πολύς: "polýs" or "many"; and πτυχή: "ptychē" or "fold, layer". Because the winged altar can display different scenes on weekdays, Sundays or holidays, based on the motifs and type of decoration (painted panels or reliefs), it is also called a liturgical altar.
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.