In chess problems, retrograde analysis is a technique employed to determine which moves were played leading up to a given position. While this technique is rarely needed for solving ordinary chess problems, there is a whole subgenre of chess problems in which it is an important part; such problems are known as retros. Retros may ask, for example, for a mate in two, but the main puzzle is in explaining the history of the position. This may be important to determine, for example, if castling is disallowed or an en passant pawn capture is possible. Other problems may ask specific questions relating...

Pleaching or plashing is a technique of interweaving living and dead branches through a hedge for stock control. Trees are planted in lines, the branches are woven together to strengthen and fill any weak spots until the hedge thickens. Branches in close contact may grow together, due to a natural phenomenon called inosculation, a natural graft. Pleach also means weaving of thin, whippy stems of trees to form a basketry effect. == HistoryEdit == Pleaching or plashing (an early synonym) was common in gardens from late medieval times to the early eighteenth century, to create shaded paths, or...