Dodgson's method of swaps needed to make him a winner) is an NP-complete problem by reduction from Exact Cover by 3-Sets (X3C). Dodgson's method Dodgson's method is an electoral system proposed by the author, mathematician and logician Charles Dodgson, better known as Lewis Carroll. The method is to extend the Condorcet method by swapping candidates until a Condorcet winner is found. The winner is the candidate which requires the minimum number of swaps. Dodgson proposed this voting scheme in his 1876 work "A method of taking votes on more than two issues". Given an integer "k" and an election, it is NP-complete
Campbell Dodgson the War Office; his 1918 CBE was a recognition of this work (DNB, 1941-50 : 216). He was the editor, in the 1920s, of "The Print Collector’s Quarterly". He was also a contributor to the "Burlington Magazine" and to the Dictionary of National Biography. Dodgson married Frances Catherine Spooner, daughter of William Archibald Spooner (Warden of New College and the eponymous author of 'Spoonerisms'), in 1913 (DNB, 1941-50 : 216). Dodgson gave generously to the British Museum during his Keepership, but at the same time amassed a very large collection of over 5,000 prints which he bequeathed to the Museum.