Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 2048 is (PSPACE) Hard, but Sometimes Easy   We prove that a variant of 2048, a popular online puzzle game, is
PSPACE-Complete. Our hardness result holds for a version of the problem where
the player has oracle access to the computer player's moves. Specifically, we
show that for an $n \times n$ game board $\mathcal{G}$, computing a sequence of
moves to reach a particular configuration $\mathbb{C}$ from an initial
configuration $\mathbb{C}_0$ is PSPACE-Complete. Our reduction is from
Nondeterministic Constraint Logic (NCL). We also show that determining whether
or not there exists a fixed sequence of moves $\mathcal{S} \in \{\Uparrow,
\Downarrow, \Leftarrow, \Rightarrow\}^k$ of length $k$ that results in a
winning configuration for an $n \times n$ game board is fixed-parameter
tractable (FPT). We describe an algorithm to solve this problem in $O(4^k n^2)$
time.

29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ