User Tools

Site Tools


problem:simple_shift_repetition_game

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

problem:simple_shift_repetition_game [2013/11/21 11:18]
tarafife created
problem:simple_shift_repetition_game [2013/11/21 11:18] (current)
tarafife
Line 2: Line 2:
 ==== Problem ==== ==== Problem ====
 Consider the set of simple shift permutations $H=\{\phi_n\mid n\in \mathbb{Z}\}$ on a 26 letter alphabet. We've shown that there are 26 different functions in this set.  Consider the following game. Consider the set of simple shift permutations $H=\{\phi_n\mid n\in \mathbb{Z}\}$ on a 26 letter alphabet. We've shown that there are 26 different functions in this set.  Consider the following game.
-* The first player picks an element $\sigma_1\in H$. They then remove from $H$ the span of $\sigma_1$ (so everything generated by $\{\sigma_1\}$).  +  * The first player picks an element $\sigma_1\in H$. They then remove from $H$ the span of $\sigma_1$ (so everything generated by $\{\sigma_1\}$).  
-* The second player now chooses an element $\sigma_2\in H$ that hasn't yet been removed. They then remove from $H$ any element in the span of $\{\sigma_1,\sigma_2\}$. At this stage, any permutation that can be written as a composition combination of the permutations $\sigma_1$ and $\sigma_2$ has been removed.  +  * The second player now chooses an element $\sigma_2\in H$ that hasn't yet been removed. They then remove from $H$ any element in the span of $\{\sigma_1,\sigma_2\}$. At this stage, any permutation that can be written as a composition combination of the permutations $\sigma_1$ and $\sigma_2$ has been removed.  
-* Players alternate taking turns, choosing an element $\sigma_k\in H$ that hasn't been removed in a previous stage, and then removing from $H$ any element in the span of $\{\sigma_1,\sigma_2,\ldots,\sigma_k\}$.   +  * Players alternate taking turns, choosing an element $\sigma_k\in H$ that hasn't been removed in a previous stage, and then removing from $H$ any element in the span of $\{\sigma_1,\sigma_2,\ldots,\sigma_k\}$.   
-* Whoever take the last element of $H$ wins. The game can also be played as a misere game. +  * Whoever take the last element of $H$ wins. The game can also be played as a misere game. 
 Answer the following questions. Answer the following questions.
   - Player 1 takes $\phi_6$.  Which elements should be removed from $H$   - Player 1 takes $\phi_6$.  Which elements should be removed from $H$
problem/simple_shift_repetition_game.1385050689.txt.gz · Last modified: 2013/11/21 11:18 by tarafife