GNU PROLOG                                ==========INTRODUCTION************GNU Prolog is a native Prolog compiler with constraint solving over finitedomains (FD) developed by Daniel Diaz (http://cri-dist.univ-paris1.fr/diaz/)Last information can be found athttp://www.gnu.org/software/prologor better athttp://www.gprolog.org.A lot of work has been devoted to the ISO compatibility. GNU Prolog is veryclose to the ISO standard.Here are some features of GNU Prolog:Prolog system:   - conforms to the ISO standard for Prolog (integer/floating arithmetic,     streams, dynamic code, exceptions).   - clause indexing.   - a lot of extensions: global variables, definite clause grammars (DCG),     sockets interface, operating system interface,...   - more than 300 Prolog built-in predicates.   - Prolog debugger and a low-level WAM debugger.   - line editing facility under the interactive interpreter with completion     on atoms.   - powerful bidirectional interface between Prolog and C.Compiler:   - native-code compiler producing stand alone executables.   - simple command-line compiler accepting a wide variety of files:     Prolog files, C files, WAM files,...   - direct generation of assembly code 15 times faster than wamcc + gcc.   - most of unused built-in predicates are not linked (to reduce the size     of the executables).   - compiled predicates (native-code) as fast as wamcc on average.   - consulted predicates (byte-code) 5 times faster than wamcc.Constraint solver:   - FD variables well integrated into the Prolog environment (full     compatibility with Prolog variables and   - integers). No need for explicit FD declarations.   - very efficient FD solver (comparable to commercial solvers).   - high-level constraints can be described in terms of simple primitives.   - a lot of predefined constraints: arithmetic constraints, boolean     constraints, symbolic constraints, reified constraints,...   - several predefined enumeration heuristics.   - the user can define his own new constraints.   - more than 50 FD built-in constraints/predicates.PORTS*****GNU Prolog is currently ported to the following architectures:   - ix86 / GNU/Linux   - ix86 / Win32 using Cygwin (see file src/WINDOWS-OLD)   - ix86 / Win32 using MinGW  (see file src/WINDOWS-OLD)   - ix86 / Win32 using MSVC++ (see file src/WINDOWS-OLD)   - ix86 / SCO   - ix86 / Solaris   - ix86 / FreeBSD   - ix86 / OpenBSD   - ix86 / NetBSD   - ix86 / Darwin (Mac OS X)   - x86_64 / GNU/Linux   - x86_64 / Solaris   - x86_64 / Win64 using MinGW64 (see file src/WINDOWS)   - x86_64 / Win64 using MSVC++  (see file src/WINDOWS)   - x86_64 / Darwin (Mac OS X)   - PowerPC / GNU/Linux   - PowerPC / Darwin (Mac OS X)   - PowerPC / NetBSD   - sparc / SunOS (4.1.3 or higher)   - sparc / Solaris   - sparc / NetBSD   - sparc64 / Solaris   - sparc64 / OpenBSD   - alpha / GNU/Linux   - alpha / OSF1   - mips / irix   - arm 32bits / GNU/Linux (armv6, armv7)    - arm 64bits (aarch64)/ GNU/Linux (armv8)   - arm 64bits (aarch64) / Darwin (Mac OS X) (armv8)   - RISC-V 64bits / GNU/LinuxINSTALLATION************Please refer to the INSTALL file (in the same directory)USING GNU PROLOG****************Be sure that adequate environment variables are set (see INSTALL)You can then invoke the top-level using:gprologand the compiler using:gplc FILEThe simplest way to compile a Prolog file 'prog.pl' is then:gplc prog.plwhich will produce the executable called prog (use gplc --help to have abrief overview of available options).Refer to the documentation for more information (see below).WINDOWS*******In Microsoft Windows if you intend to use the gplc compiler as described inthe documentation you need to ascertain the following conditions aremet:   - for the port compiled with Microsoft Visual C++ (aka MSVC++)     (tested with Microsoft Visual Studio 2019 Community) you'll need     MinGW as.exe (renamed as mingw-as.exe) installed and the cl.exe     compiler (used mainly as linker by GNU Prolog) available in      your session path (alternatively link.exe is used).   - for the ports compiled either with MinGW, the gcc toolchain     must be installed and available in your session path.Observing these needs you'll also will be able to do the mixedlanguage programming, as the examples included in the ExamplesCdirectory. However you'll need to write your own Makefile as the oneprovided is for gplc calling 'gcc' and the options passed by GNUProlog will not work (see file ExamplesC/README).DOCUMENTATION*************The directory doc contains various versions of the manual. Refer to thefile doc/README for more information.An in-line HTML version can be accessed from the GNU Prolog web page.WEB***The GNU Prolog web site is:http://www.gnu.org/software/prolog/or also (primary web site):http://www.gprolog.org/MAILING LIST************To communicate with other GNU Prolog users and/or implementors send a mail tousers-prolog@gnu.org. To (un)subscribe to this mailing list send a mail tousers-prolog-request@gnu.org with (un)subscribe in the subject line.BUGS****Please report bugs to bug-prolog@gnu.org. To (un)subscribe to this mailinglist send a mail to bug-prolog-request@gnu.org with (un)subscribe in thesubject line.COPYING*******GNU Prolog is free software. Since version 1.4.0, GNU Prolog distributedunder a dual license: LGPL or GPL. So, you can redistribute it and/or modifyit under the terms of either:  * the GNU Lesser General Public License (LGPL) as published by the Free    Software Foundation; either version 3 of the License, or (at your option)    any later version.or   * the GNU General Public License (GPL) as published by the Free Software    Foundation; either version 2 of the License, or (at your option) any    later version.  or both in parallel (as here).GNU Prolog is distributed in the hope that it will be useful, but WITHOUT ANYWARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FORA PARTICULAR PURPOSE. See the GNU General Public License for more details.You should have received copies of the GNU General Public License and the GNULesser General Public License along with this program. If not, seehttp://www.gnu.org/licenses/.Remark: versions of GNU Prolog prior to 1.4.0 were entirely released underthe GNU General Public License (GPL).