Provided by:
sgt-puzzles_9411-1_i386 
NAME
bridges - topological deduction game
SYNOPSIS
bridges [--generate n] [--print wxh [--with-solutions] [--scale n]
[--colour]] [game-parameters|game-ID|random-seed]
bridges --version
DESCRIPTION
You have a set of islands distributed across the playing area. Each
island contains a number. Your aim is to connect the islands together
with bridges, in such a way that:
+o Bridges run horizontally or vertically.
+o The number of bridges terminating at any island is equal to the
number written in that island.
+o Two bridges may run in parallel between the same two islands,
but no more than two may do so.
+o No bridge crosses another bridge.
+o All the islands are connected together.
There are some configurable alternative modes, which involve changing
the parallel-bridge limit to something other than 2, and introducing
the additional constraint that no sequence of bridges may form a loop
from one island back to the same island. The rules stated above are the
default ones.
Credit for this puzzle goes to Nikoli
(http://www.nikoli.co.jp/puzzles/14/index-e.htm).
Bridges was contributed to this collection by James Harvey.
Bridges controls
To place a bridge between two islands, click the mouse down on one
island and drag it towards the other. You do not need to drag all the
way to the other island; you only need to move the mouse far enough for
the intended bridge direction to be unambiguous. (So you can keep the
mouse near the starting island and conveniently throw bridges out from
it in many directions.)
Doing this again when a bridge is already present will add another
parallel bridge. If there are already as many bridges between the two
islands as permitted by the current game rules (i.e. two by default),
the same dragging action will remove all of them.
If you want to remind yourself that two islands definitely do not have
a bridge between them, you can right-drag between them in the same way
to draw a 'non-bridge' marker.
If you think you have finished with an island (i.e. you have placed all
its bridges and are confident that they are in the right places), you
can mark the island as finished by left-clicking on it. This will
highlight it and all the bridges connected to it, and you will be
prevented from accidentally modifying any of those bridges in future.
Left-clicking again on a highlighted island will unmark it and restore
your ability to modify it.
You can also use the cursor keys to move around the grid: if possible
the cursor will always move orthogonally, otherwise it will move
towards the nearest island to the indicated direction. Pressing the
return key followed by a cursor key will lay a bridge in that direction
(if available); pressing the space bar followed by a cursor key will
lay a 'non-bridge' marker.
You can mark an island as finished by pressing the return key twice.
Violations of the puzzle rules will be marked in red:
+o An island with too many bridges will be highlighted in red.
+o An island with too few bridges will be highlighted in red if it
is definitely an error (as opposed to merely not being finished
yet): if adding enough bridges would involve having to cross
another bridge or remove a non-bridge marker, or if the island
has been highlighted as complete.
+o A group of islands and bridges may be highlighted in red if it
is a closed subset of the puzzle with no way to connect it to
the rest of the islands. For example, if you directly connect
two 1s together with a bridge and they are not the only two
islands on the grid, they will light up red to indicate that
such a group cannot be contained in any valid solution.
+o If you have selected the (non-default) option to disallow loops
in the solution, a group of bridges which forms a loop will be
highlighted.
(All the actions described below are also available.)
Bridges parameters
These parameters are available from the 'Custom...' option on the
'Type' menu.
Width, Height
Size of grid in squares.
Difficulty
Difficulty level of puzzle.
Allow loops
This is set by default. If cleared, puzzles will be generated in
such a way that they are always soluble without creating a loop,
and solutions which do involve a loop will be disallowed.
Max. bridges per direction
Maximum number of bridges in any particular direction. The
default is 2, but you can change it to 1, 3 or 4. In general,
fewer is easier.
%age of island squares
Gives a rough percentage of islands the generator will try and
lay before finishing the puzzle. Certain layouts will not manage
to lay enough islands; this is an upper bound.
Expansion factor (%age)
The grid generator works by picking an existing island at random
(after first creating an initial island somewhere). It then
decides on a direction (at random), and then works out how far
it could extend before creating another island. This parameter
determines how likely it is to extend as far as it can, rather
than choosing somewhere closer.
High expansion factors usually mean easier puzzles with fewer possible
islands; low expansion factors can create lots of tightly-packed
islands.
Common actions
These actions are all available from the 'Game' menu and via keyboard
shortcuts, in addition to any game-specific actions.
(On Mac OS X, to conform with local user interface standards, these
actions are situated on the 'File' and 'Edit' menus instead.)
New game ('N', Ctrl+'N')
Starts a new game, with a random initial state.
Restart game
Resets the current game to its initial state. (This can be
undone.)
Load Loads a saved game from a file on disk.
Save Saves the current state of your game to a file on disk.
The Load and Save operations preserve your entire game history
(so you can save, reload, and still Undo and Redo things you had
done before saving).
Print Where supported (currently only on Windows), brings up a dialog
allowing you to print an arbitrary number of puzzles randomly
generated from the current parameters, optionally including the
current puzzle. (Only for puzzles which make sense to print, of
course - it's hard to think of a sensible printable
representation of Fifteen!)
Undo ('U', Ctrl+'Z', Ctrl+'_')
Undoes a single move. (You can undo moves back to the start of
the session.)
Redo ('R', Ctrl+'R')
Redoes a previously undone move.
Copy Copies the current state of your game to the clipboard in text
format, so that you can paste it into (say) an e-mail client or
a web message board if you're discussing the game with someone
else. (Not all games support this feature.)
Solve Transforms the puzzle instantly into its solved state. For some
games (Cube) this feature is not supported at all because it is
of no particular use. For other games (such as Pattern), the
solved state can be used to give you information, if you can't
see how a solution can exist at all or you want to know where
you made a mistake. For still other games (such as Sixteen),
automatic solution tells you nothing about how to get to the
solution, but it does provide a useful way to get there quickly
so that you can experiment with set-piece moves and
transformations.
Some games (such as Solo) are capable of solving a game ID you
have typed in from elsewhere. Other games (such as Rectangles)
cannot solve a game ID they didn't invent themself, but when
they did invent the game ID they know what the solution is
already. Still other games (Pattern) can solve some external
game IDs, but only if they aren't too difficult.
The 'Solve' command adds the solved state to the end of the undo
chain for the puzzle. In other words, if you want to go back to
solving it yourself after seeing the answer, you can just press
Undo.
Quit ('Q', Ctrl+'Q')
Closes the application entirely.
Specifying games with the game ID
There are two ways to save a game specification out of a puzzle and
recreate it later, or recreate it in somebody else's copy of the same
puzzle.
The 'Specific' and 'Random Seed' options from the 'Game' menu (or the
'File' menu, on Mac OS X) each show a piece of text (a 'game ID') which
is sufficient to reconstruct precisely the same game at a later date.
You can enter either of these pieces of text back into the program (via
the same 'Specific' or 'Random Seed' menu options) at a later point,
and it will recreate the same game. You can also use either one as a
command line argument (on Windows or Unix); see below for more detail.
The difference between the two forms is that a descriptive game ID is a
literal description of the initial state of the game, whereas a random
seed is just a piece of arbitrary text which was provided as input to
the random number generator used to create the puzzle. This means that:
+o Descriptive game IDs tend to be longer in many puzzles (although
some, such as Cube (cube(6)), only need very short
descriptions). So a random seed is often a quicker way to note
down the puzzle you're currently playing, or to tell it to
somebody else so they can play the same one as you.
+o Any text at all is a valid random seed. The automatically
generated ones are fifteen-digit numbers, but anything will do;
you can type in your full name, or a word you just made up, and
a valid puzzle will be generated from it. This provides a way
for two or more people to race to complete the same puzzle: you
think of a random seed, then everybody types it in at the same
time, and nobody has an advantage due to having seen the
generated puzzle before anybody else.
+o It is often possible to convert puzzles from other sources (such
as 'nonograms' or 'sudoku' from newspapers) into descriptive
game IDs suitable for use with these programs.
+o Random seeds are not guaranteed to produce the same result if
you use them with a different version of the puzzle program.
This is because the generation algorithm might have been
improved or modified in later versions of the code, and will
therefore produce a different result when given the same
sequence of random numbers. Use a descriptive game ID if you
aren't sure that it will be used on the same version of the
program as yours.
(Use the 'About' menu option to find out the version number of
the program. Programs with the same version number running on
different platforms should still be random-seed compatible.)
A descriptive game ID starts with a piece of text which encodes the
parameters of the current game (such as grid size). Then there is a
colon, and after that is the description of the game's initial state. A
random seed starts with a similar string of parameters, but then it
contains a hash sign followed by arbitrary data.
If you enter a descriptive game ID, the program will not be able to
show you the random seed which generated it, since it wasn't generated
from a random seed. If you enter a random seed, however, the program
will be able to show you the descriptive game ID derived from that
random seed.
Note that the game parameter strings are not always identical between
the two forms. For some games, there will be parameter data provided
with the random seed which is not included in the descriptive game ID.
This is because that parameter information is only relevant when
generating puzzle grids, and is not important when playing them. Thus,
for example, the difficulty level in Solo (solo(6)) is not mentioned in
the descriptive game ID.
These additional parameters are also not set permanently if you type in
a game ID. For example, suppose you have Solo set to 'Advanced'
difficulty level, and then a friend wants your help with a 'Trivial'
puzzle; so the friend reads out a random seed specifying 'Trivial'
difficulty, and you type it in. The program will generate you the same
'Trivial' grid which your friend was having trouble with, but once you
have finished playing it, when you ask for a new game it will
automatically go back to the 'Advanced' difficulty which it was
previously set on.
The 'Type' menu
The 'Type' menu, if present, may contain a list of preset game
settings. Selecting one of these will start a new random game with the
parameters specified.
The 'Type' menu may also contain a 'Custom' option which allows you to
fine-tune game parameters. The parameters available are specific to
each game and are described in the following sections.
Specifying game parameters on the command line
(This section does not apply to the Mac OS X version.)
The games in this collection deliberately do not ever save information
on to the computer they run on: they have no high score tables and no
saved preferences. (This is because I expect at least some people to
play them at work, and those people will probably appreciate leaving as
little evidence as possible!)
However, if you do want to arrange for one of these games to default to
a particular set of parameters, you can specify them on the command
line.
The easiest way to do this is to set up the parameters you want using
the 'Type' menu (see above), and then to select 'Random Seed' from the
'Game' or 'File' menu (see above). The text in the 'Game ID' box will
be composed of two parts, separated by a hash. The first of these parts
represents the game parameters (the size of the playing area, for
example, and anything else you set using the 'Type' menu).
If you run the game with just that parameter text on the command line,
it will start up with the settings you specified.
For example: if you run Cube (see cube(6)), select 'Octahedron' from
the 'Type' menu, and then go to the game ID selection, you will see a
string of the form 'o2x2#338686542711620'. Take only the part before
the hash ('o2x2'), and start Cube with that text on the command line:
'cube o2x2'.
If you copy the entire game ID on to the command line, the game will
start up in the specific game that was described. This is occasionally
a more convenient way to start a particular game ID than by pasting it
into the game ID selection box.
(You could also retrieve the encoded game parameters using the
'Specific' menu option instead of 'Random Seed', but if you do then
some options, such as the difficulty level in Solo, will be missing.
See above for more details on this.)
Unix command-line options
(This section only applies to the Unix port.)
In addition to being able to specify game parameters on the command
line (see above), there are various other options:
--game
--load These options respectively determine whether the command-line
argument is treated as specifying game parameters or a save file
to load. Only one should be specified. If neither of these
options is specified, a guess is made based on the format of the
argument.
--generate n
If this option is specified, instead of a puzzle being
displayed, a number of descriptive game IDs will be invented and
printed on standard output. This is useful for gaining access to
the game generation algorithms without necessarily using the
frontend.
If game parameters are specified on the command-line, they will
be used to generate the game IDs; otherwise a default set of
parameters will be used.
The most common use of this option is in conjunction with
--print, in which case its behaviour is slightly different; see
below.
--print wxh
If this option is specified, instead of a puzzle being
displayed, a printed representation of one or more unsolved
puzzles is sent to standard output, in PostScript format.
On each page of puzzles, there will be w across and h down. If
there are more puzzles than wxh, more than one page will be
printed.
If --generate has also been specified, the invented game IDs
will be used to generate the printed output. Otherwise, a list
of game IDs is expected on standard input (which can be
descriptive or random seeds; see above), in the same format
produced by --generate.
For example:
net --generate 12 --print 2x3 7x7w | lpr
will generate two pages of printed Net puzzles (each of which
will have a 7x7 wrapping grid), and pipe the output to the lpr
command, which on many systems will send them to an actual
printer.
There are various other options which affect printing; see
below.
--save file-prefix [ --save-suffix file-suffix ]
If this option is specified, instead of a puzzle being
displayed, saved-game files for one or more unsolved puzzles are
written to files constructed from the supplied prefix and/or
suffix.
If --generate has also been specified, the invented game IDs
will be used to generate the printed output. Otherwise, a list
of game IDs is expected on standard input (which can be
descriptive or random seeds; see above), in the same format
produced by --generate.
For example:
net --generate 12 --save game --save-suffix .sav
will generate twelve Net saved-game files with the names
game0.sav to game11.sav.
--version
Prints version information about the game, and then quits.
The following options are only meaningful if --print is also specified:
--with-solutions
The set of pages filled with unsolved puzzles will be followed
by the solutions to those puzzles.
--scale n
Adjusts how big each puzzle is when printed. Larger numbers make
puzzles bigger; the default is 1.0.
--colour
Puzzles will be printed in colour, rather than in black and
white (if supported by the puzzle).
SEE ALSO
Full documentation in /usr/share/doc/sgt-puzzles/puzzles.txt.gz.