1 files changed, 57 insertions, 36 deletions

diff --git a/INSTALL b/INSTALL
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--- a/INSTALL
+++ b/INSTALL
@@ -4,57 +4,78 @@ Nissy is available at https://nissy.tronto.net
 
 # Requirements
 
-A full installation of nissy requires about 3Gb of space,
-of which 2.3Gb are occupied by the huge pruning table for fast optimal solving,
-and running it requires the same amount of RAM.
-One can choose to never use this function and not to install the relative
-pruning table. There is an alternative (slower)
-optimal solving function that uses about 500Mb of RAM.
+A full installation of nissy requires about 3Gb of space, of which
+2.3Gb are occupied by the huge pruning table for fast optimal solving,
+and running it requires the same amount of RAM.  One can choose to never
+use this function and not to install the relative pruning table. There
+is an alternative (slower) optimal solving function that uses about
+500Mb of RAM.  When generating the pruning tables automatically (see
+the section Tables below), at least 5.3Gb or RAM are required.
 
 # Installation
 
 ## On Windows
 
 Try downloading and executing in a terminal the file nissy.exe, then
-follow the instructions in the Tables section below for
-installing the pruning tables.
-If nissy.exe does not work, you can try following the UNIX instructions
-in WSL (Windows Subsystem for Linux) or in a similar environment.
-
-Sorry for the inconvenience, I don't have a Windows machine to test this on.
+follow the instructions in the Tables section below for installing the
+pruning tables. If nissy.exe does not work, you can try following the
+UNIX instructions in WSL (Windows Subsystem for Linux) or in a similar
+environment.
 
 ## On a UNIX system:
 
-Edit the Makefile to match your local configuration (usually not necessary, but you
-may want to change the PREFIX variable) and run make, followed by make install.
-Follow the instructions below to install the pruning tables.
+Download the source archive (.tar.gz). Extract it with your favorite
+archive program, for example with
+
+        tar -xvzf nissy-VERSION.tar.gz
+
+Open a terminal in the directory just extracted. If you wish, edit the
+Makefile to match your local configuration (this is usually not necessary,
+but you may want to change the PREFIX variable to change the installation
+path) and run
+
+        make
+
+followed by
+
+        make install
+
+Then follow the instructions below to install the pruning tables. 
 
 ## Tables
-Nissy needs to generate certain large tables to work. These tables are by default
-generated the first time they are needed (e.g the first time you ask to solve a
-certain step) and then saved to a file. Whenever these tables are needed again,
-nissy simply loads the corresponding file from the hard disk.
 
-The very large table for optimal solving can take some time to generate
-(about 1.5 hours on my fairly old but decent laptop, using 8 CPU threads).
-In order to generate it you need at least 5Gb of RAM.
-All other tables are much faster.
+Once you have installed nissy, run
 
-You can ask nissy to generate all the tables it will ever need with the gen
-command. It is recommended to use more than one thread, if your CPU has them.
-For example, you can run:
+        nissy gen
 
-nissy gen -t 8
+to generate all the tables that Nissy will ever need. Running this
+command requires around 5.3Gb of RAM, and it can take some time (about
+40 minutes on my fairly old but decent laptop, with 8 CPU threads).
 
-to generate all tables using 8 threads.
+Some unnecessary technical detail: by default this command is going to
+use at most 64 threads. If you want you can choose to use more threads
+(if your CPU is very powerful) or fewer threads (if you for example
+want to run this command in the background while you do other stuff)
+with the -t option, for example nissy gen -t 1.
 
-Alternatively, you can simply download all the tables and copy them into the
-correct folder (see manual page, ENVIRONMENT section). On UNIX operating
-systems this folder is either .nissy/tables in the user's home directory or
-$XDG_DATA_HOME/nissy/tables if the XDG variable is configured. On Windows
-it is the same directory as the nissy.exe executable file.
+Alternatively, you can download all the tables (1.7Gb) and copy them
+into the correct folder (see manual page, ENVIRONMENT section). On UNIX
+operating systems this folder is either .nissy/tables in the user's
+home directory or $XDG_DATA_HOME/nissy/tables if the XDG variable
+is configured. On Windows it is the same directory as the nissy.exe
+executable file.
 
 You can downloads all the tables from the following link:
-        https://nissy.tronto.net/nissy-tables-2.0.zip
-The version 2.0 at the end of the file name is only indicative.
-Later versions will use the same tables, unless otherwise specified.
+
+        https://nissy.tronto.net/nissy-tables-2.0.2.zip
+
+# Upgrading
+
+If you already have nissy installed and you want to upgrade to a more
+recent version, you can simply repeat the installation process:
+* On Windows: simply replace nissy.exe with the new file with the same name.
+* On UNIX systems: download the new version of the source code, extract it
+  in a new folder and run make and make install again.
+
+Between each version new table files might have been added, or old ones
+may be not used anymore. Nissy will deal with this automatically.