.Dd November 2021
.Dt NISSY 1
.Os
.Sh NAME
.Nm nissy
.Nd a Rubik's cube solver and FMC assistant
.
.Sh SYNOPSIS
.Nm
.Op Fl b
.Nm
.Ar command
.Op options...
.
.Sh DESCRIPTION
.Nm
is a Rubik's Cube solver. 
It uses techniques from Herbert Kociemba's Cube Explorer and
Tomas Rokicki's nxopt. With 4 cores at 2.5GHz and using less than 3Gb
of RAM, Nissy can find the optimal solution for a random Rubik's cube position
in about a minute on average.
Nissy can also solve different substeps of the Thistlethwaite's algorithm and more.
.Pp
When run without any argument an interactive shell is launched, otherwise
the provided
.Ar command
is executed and nissy terminates. If the option
.Fl b
is given, every argument after it is ignored and the shell is launched without
any prompt or welcome message. This can be used to run nissy in batch mode,
for example writing a list of commands in a
.Ar file
(one per line) and running
.Ar nissy -b < file
.Pp
The commands that can be run in the interactive shell are the same that can
be run non-interactively and are provided below.
.
.Sh COMMANDS
The available
.Ar commands
are the following:
.
.Bl -tag -width Ds
.
.It Nm cleanup Ar scramble
Rewrites the given scramble using only the 18 base (HTM) moves and at most two
rotations at the end. If
Ar scramble
uses NISS, all moves done on normal scramble are written first, followed by
all moves done on inverse.
.
.It Nm commands
List all available commands.
.
.It Nm freemem
Release some large tables from memory. You can use this command in case
you want to keep nissy open without using too much RAM.
.
.It Nm gen Op Fl t Ar N
Generate all tables used by nissy. Run this to complete your installation.
If
.Ar N
is specified,
.Ar N
CPU threads will be used (defaults to 64, use less only if you don't want
nissy to use all of your CPU resources).
.
.It Nm help Op Ar command
Display help. If no
.Ar command
is given, a generic help message is printed, otherwise a specific help
relative to
.Ar command
is returned.
.
.It Nm invert Ar scramble
Invert the given scramble.
.
.It Nm print Ar scramble
Display a text-only description of the cube obtained after applying
.Ar scramble .
.
.It Nm quit
Quit nissy.
.
.It Nm scramble Oo Fl n Ar N Oc Oo Ar type Oc
Print a randomly-generated (random position) scramble
.
If
.Ar N
is given, it produces
.Ar N
scrambles.
.Ar type
can be specified to be one of the following:
.Bl -tag -width Ds
.It Ar corners
Scramble with solved edges (only cornes are scrambled).
.It Ar dr
Scramble with solved DR on U/D.
.It Ar edges
Scramble with solved corners (only edges are scrambled).
.It Ar eo
Scramble with solved EO on F/B axis.
.It Ar fmc
Scramble the full cube and the resulting scramble starts and ends with
the moves R\(aq U\(aq F.
.It Ar htr
Scramble with HTR solved.
.El
.
.It Nm solve Ar step Oo Ar options Oc Ar scramble
Solve the given
.Ar step
on the given
.Ar scramble.
By default it finds only one (shortest) solution, without using niss, and it
displays the number of moves at the end of the line.
.
The options for the
.Ar solve
command are the following:
.
.Bl -tag -width Ds
.
.It Fl a
Print all solutions: some solutions are filtered out by default for some
steps, for examples EOs that finish with F\(aq, with this options they are not.
.
.It Fl c
Display only the number of solutions found, not the solutions themselves.
.
.It Fl m Ar min
Only look for solution that are at least
.Ar min
moves long.
.
.It Fl M Ar MAX
Only look for solution that are at most
.Ar MAX
moves long.
.
.It Fl n Ar N
Try to find
.Ar N
solutions. By default and unless the
.Fl M
or
.Fl o
options are used, at most one solution is returned. 
If at least one of
.Fl M
and
.Fl o
is used, all the solutions found within the given bounds are returned.
The option
.Fl s
overwrites these default behaviors and at most
.Ar N
solutions are returned, still satisfiyng the other constraints.
.
.It Fl N
Allow use of NISS.
.
.It Fl o
Only find solutions that require the minimum number of moves.
.
.It Fl O Ar N
Only find solutions that require at most
.Ar N
moves more than the optimal solution. If
.Ar N
is 0, this is equivalent to
.Fl o
.
.It Fl p
Plain style: do not print the number of moves.
.
.It Fl t Ar N
Use
.Ar N
CPU threads. By default nissy uses only 1 thread. Using more than one
thread will improve performance, but the optimal number depends on your
machine and operating system. Generally, using one less than the number
of threads of your CPU works quite well.
.
.It Fl v
Verbose mode: print some information during the search and print each solution
as it is found instead of only printing them all together at the end.
.
.
.El
.
.It Nm steps
List all available
.Ar steps
for the
.Ar solve
command.
.
.It Nm twophase Ar scramble
Find a solution using a two-phase method. This does not guarantee
to return an optimal solution (and in fact most often it does not),
but it is very fast.
.
.It Nm unniss Ar scramble
Rewrite the scramble without using NISS.
.
.It Nm version
Display version information.
.
.El
.
.Sh SCRAMBLES
All the commands above that accept a scramble also accept a
.Fl Nm i
option with no arguments.
If this option is given, multiple scrambles are read from standard
input (one per line) until and EOF is found, at which point stdin is cleared.
.
.Sh ENVIRONMENT
Data is stored in the folder pointed to by
.Nm $NISSYDATA.
If that variable is unset the folder
.Nm $XDG_DATA_HOME/nissy
or
.Nm $HOME/.nissy
is used instead. If none of this environment variables is defined
(e.g. in a non-UNIX system), the current folder is used.
.
.Sh EXAMPLES
.Pp
The command:
.Dl nissy solve -v -O 1 \(dqR\(aqU\(aqFD2L2FR2U2R2BD2LB2D\(aqB2L\(aqR\(aqBD2BU2LU2R\(aqU\(aqF\(dq
Returns:
.Dl Searching depth 0
.Dl Searching depth 1
.Dl (some more lines)
.Dl Searching depth 16
.Dl D2 F\(aq U2 D2 F\(aq L2 D R2 D F B2 R\(aq L2 F\(aq U\(aq D
.Dl Searching depth 17
.Dl D2 F\(aq U2 D2 F\(aq L2 D R2 D F B2 R\(aq L2 F\(aq U\(aq D (16)
Notice that the solution is printed twice: the first time it is printed as soon
as it is found as requested by the -v option.
.Pp
The command:
.Dl nissy solve eofb -m 4 -M 5 -N -n 6 \(dqR\(aqU\(aqFD2L2 FR2 U2R2BD2 L B2 D\(aq B2 L\(aq R\(aq\(dq
Returns:
.Dl U B U\(aq B (4)
.Dl U (B R\(aq B) (4)
.Dl (U B R\(aq B) (4)
.Dl U2 F R2 F (4)
.Dl U2 B U2 B (4)
.Dl (U2 B R\(aq B) (4)
.Pp
On a UNIX shell, the composite command
.Dl nissy scramble -n 2 | nissy solve -i > file.txt
Generates two random scrambles, solves them and saves the result to file.txt.
The file will look something like this:
.Dl >>> Line: D U2 F D B\(aq F L2 D\(aq F2 R2 L B2 L\(aq U2 B2 R F2 L\(aq D2
.Dl U2 R2 F2 L B2 D\(aq R2 D\(aq F U L2 B\(aq U\(aq R2 D2 R2 U (17)
.Dl >>> Line: D B R U\(aq B\(aq L2 U L U D2 R L B2 U2 L2 U2 R U2 B2 L F2
.Dl D\(aq F R\(aq D B L2 B R2 L U L U2 B D\(aq U R U F2 (18)
.
.Sh AUTHORS
.An Sebastiano Tronto Aq Mt sebastiano.tronto@gmail.com
.
.Sh SOURCE CODE
Source code is available at
.Lk https://nissy.tronto.net