TOT 272 1990 Autumn A J6 n different cards
Source:
June 8, 2024
combinatorics
Problem Statement
A deck consists of different cards. A move consists of taking out a group of cards in sequence from some place in the deck, and putting it back someplace else without changing the order within the group or turning any cards over. We are required to reverse the order of cards in the deck by such moves.(a) Prove that for , this can be done in moves. (b) Prove that for , this
i. can be done in moves,
ii. can’t be done in moves,
iii. can’t be done in moves.
(SM Voronin, Tchelyabinsk)