OrgPad logo

Dice puzzles in game Zero Escape: Virtue's Last Reward

Created by Pavel Klavík

Mathematics behind puzzle with dice where dice are flipped along their sides on a grid. The goal is to get dice from one configuration into another one. It is discussed when it is precisely possible and when it is impossible.

#game, #mathematics, #puzzle

Dice puzzles in game Zero Escape: Virtue's Last Reward

Cube has 24 rotational symmetries

For the count, it is possible to map a vertex to all others (8 possibilities) and then further rotate the cube along this vertex in three ways, so 24 in total.

Every rotation maps each pair of opposite vertices to a pair of opposite vertices. There are four pairs of opposite vertices which can be permuted arbitrarily. Therefore, the structure of rotations is isomorphic to S4.

Blue generator

Rotating the cube to the front.

.

image

.

image

Symmetries can be divided into two groups by parity

Depicted green and purple in the picture.

These generators transform one parity into the other.

Two generators of rotational symmetries of the cube

.

image

.

image

.

image

.

image

.

image

.

image

.

image

.

image

.

image

.

image

.

image

.

image

Red generator

Rotating the cube to the right.

.

image

.

image

.

image

Dice puzzle

We have a die placed on a grid and we want to rotate it to neighboring grid fields and to return it back while changing its rotation. When it is possible? When the starting rotation and the target rotation belong to the same parity.

https://math.stackexchange.com/questions/502449/the-rotation-of-dice-on-a-grid

Yt553

.

image

Easy: getting the other parity is impossible

Since the number of rotations when the starting and target positions are the same is always even.

.

image

.

image

.

image

.

image

.

image

.

image

Rotate left, rotate forward, rotate right, rotate backwards

Corresponding to moving against red, along blue, along red and against blue.

.

image

.

image

.

image

.

image

.

image

Harder: we can get all die rotations of the same parity while keeping the position

For that, we consider two simple sequences of moves which clearly preserve the position. These sequences correspond to rotating a die in place along a diagonal going through two opposite vertices. There are four such rotations but we just need two to connect all 12 states.

We just look how they rotate the cube and they can be combined to get from every possible rotation to every other.

How the puzzle works

.

image

.

image

.

image

.

image

.

image

Rotate right, rotate forward, rotate left, rotate backwards

Corresponding to moving along red, along blue, against red, against blue.

.

image

.

image

These generate the full subgroup of all symmetries of one parity A₄

Slightly more symmetric drawing.

image

About the game

Zero Escape: Virtue's Last Reward is a 2012 adventure game developed by Chunsoft.

https://store.steampowered.com/app/477740/Zero_Escape_The_Nonary_Games/

Virtue%27s Last Reward 3DS Boxart