Multiplication table for the new product for n=11 and n=12
Source: IMO Longlist 1989, Problem 1
September 18, 2008
algebra unsolvedalgebra
Problem Statement
In the set S_n \equal{} \{1, 2,\ldots ,n\} a new multiplication is defined with the following properties:
(i) c \equal{} a * b is in for any
(ii) If the ordinary product is less than or equal to then a*b \equal{} a \cdot b.
(iii) The ordinary rules of multiplication hold for i.e.:
(1) a * b \equal{} b * a (commutativity)
(2) (a * b) * c \equal{} a * (b * c) (associativity)
(3) If a * b \equal{} a * c then b \equal{} c (cancellation law).
Find a suitable multiplication table for the new product for n \equal{} 11 and n \equal{} 12.