Olympiad Math Problem

This is a question from Arthur Engel: "Prove that an axb chessboard can be covered by nx1 tiles iff n|a or n|b". I have seen the solution but am not 'convinced' by it. Can anyone please help?
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πrate
πrate9mo ago
what solution did you see there is a paper on that problem, with 10-15 different solutions
SirLancelotDuLac
SirLancelotDuLacOP9mo ago
No description
SirLancelotDuLac
SirLancelotDuLacOP9mo ago
It is something like this: Colouring the pieces of the chessboard as shown and then I tried making a system of equations to show some contradiction.
πrate
πrate9mo ago
aahhh good proof if n divides a or b then you can basically cut the board into pieces that part is obvious to you right?
SirLancelotDuLac
SirLancelotDuLacOP9mo ago
Yes.
πrate
πrate9mo ago
great see it this way take n different colors start painting the board, alternating between colors if every color appears equal number of times, we are done that makes sense?
SirLancelotDuLac
SirLancelotDuLacOP9mo ago
Yeah.
πrate
πrate9mo ago
great try to see it this way now if n does not divide a or b let a= cn +r1 now you can basically prove that there will be some colors with unequal number of squares this is basically that proof
SirLancelotDuLac
SirLancelotDuLacOP9mo ago
Oh. Thanks a lot.
πrate
πrate9mo ago
i hope this makes sense i’m not able to put it very well like if it is cn+r every color will be c times except some thats what the proof is it’s very rigorous ug math required (not necessarily though 😉 )
SirLancelotDuLac
SirLancelotDuLacOP9mo ago
That is a good explanation. Thanks.
πrate
πrate9mo ago
it’s not mine i have worked on that book i read a paper related to this long back the explanation in that was similar i just put it like that wait let me cite
SirLancelotDuLac
SirLancelotDuLacOP9mo ago
Yeah. I saw the solution in the book, but got lost somewhere in between. Now I see what the author was trying to say.
πrate
πrate9mo ago
Packing a Rectangle with Congruent N-ominoes DAVID A. KLARNER McMas'ter University, Hamilton, Ontario, Canada Communicated b)' Gian-Carlo Rota Received April 1968 ABSTRACT Golomb defines a polyomino (a generalized domino) to be a finite set of rook-wise connected cells in an infinite chessboard. In this note we discuss problems concerning the packing of rectangles with congruent polyominoes. Many of these problems are unsolved.
πrate
πrate9mo ago
this is a very good proof
No description
SirLancelotDuLac
SirLancelotDuLacOP9mo ago
Will have a look at this too. Once again, thanks a ton.
πrate
πrate9mo ago
anytime :))
SirLancelotDuLac
SirLancelotDuLacOP9mo ago
+solved @πrate
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