Martin Gardner was a great science writer famous for the publication of numerous books on recreational mathematics translated into many languages.

One such book , its cover attached to this riddle is " The riddles of Sam Loyd ".

Sam Loyd (Samuel Loyd ) was a chess player occupied the 15 place worldwide, author of ingenious chess problems and puzzles maker of recreational mathematics.

One of his most famous works is dedicated to Tangram , with 700 designs.

One of his mathematical puzzles is as follows: Is it legal the marriage of a man with his widow's sister ?

-- Solving the riddle of Sam Loyd --