Release Notes

Version 5.6 (2003-06-07)

LP/MIP solver interface

• New library lib(colgen) for performing hybrid LP/CP column generation with user-specified subproblem solvers. The solutions returned by subproblem solvers are used to generate new columns - variables and their associated coefficients in the linear linking constraints and objective of the LP master problem. Subproblems may be solved by any ECLiPSe solver. In combination with the new bfs library  branch-and-price algorithms can be developed with user-specified subproblem solution and node separation methods.
• New library lib(bfs) for performing generic branch-and-bound search with alternative node ordering techniques. This library is primarily intended for use with the new colgen library in creating branch-and-price algorithms, but may be used with any node solution method. Rather than searching depth-first via the usual backtracking of ECLiPSe, open nodes are selected for expansion according to the specified node-ordering criteria: best-first, best-estimate or depth-first. The problem at each node is solved by a user-specified solver. Several variable and constraint dichotomy based node separation schemes are built-in and users may also specify application specific schemes.
• New experimental standalone eplex library, lib(s_eplex), which we hope will replace the current eplex library in a future release. In this version, the bounds for the problem variables are maintained in the external solver, rather than an ECLiPSe bounds keeper like lib(ic). The main advantages are that bounds constraints are no longer treated differently from other eplex constraints, and a generally improved performance. We encourage people to try out this library and report their experiences to us. Note that there are some incompatibilities with previous versions of eplex. Please see the eplex chapter in the constraints manual for details.
• Official release of XPRESS-MP 14 with lib(eplex). The version included with this release, 14.21, is the latest version of Xpress from Dash. Support for release 12 has been removed.

New Libraries

Changes to Libraries

lib(eplex), lib(ic_eplex)

Added  $::/2, $=/2, $=</2, $>=/2.

New options during setup: temp_dir, timeout. The location of where temporary files used by the external solver can now be specified, and this can  lead to significant improvements in performances if the temporary files were written to a relatively slow file system like NFS.

Warnings are printed when trying to load incompatible variants of this solver.

lib(eplex_relax)

The piecewise_linear_hull/3 constraint from lib(eplex_relax) has been folded into lib(eplex) and extended to work with eplex instances.  A port of this constraint has also been added to lib(ic_eplex).

lib(fd)

Added #::/2 and #::/3.

Warnings are printed when trying to use lib(fd) and lib(ic) together.

lib(ic)

Added piecewise_linear/3.

Adde #::/2, $::/2, $=/2, $>=/2, $=</2, $>/2, $</2, $\=/2.

Warnings are printed when trying to use lib(fd) and lib(ic) together.

lib(suspend)

Added a full set of equality, inequality, disequality and range constraints, and their reified versions, according to the common solver interface.

lib(graph_algorithms)

Added critical_links/2

lib(var_name)

Added get_var_name/2

lib(xml)

Upgraded to John Fletcher's release 1.6.

Development Environment

• Better integration with debugging tools.
• Added support for visualising graphs from lib(graph_algorithms) called a Network viewer.
• Can have variables on edges.
• Automatic directed, undirected and radial layout using external tools from the GraphViz project. Details at http://www.research.att.com/sw/tools/graphviz/.
• Enhancements to Desktop (and features of Network viewer)...
• Can now print the display.
• Desktop viewer now dynamically resizes to fit viewlets (no more overlapping viewlets).
• Added anti-aliasing to the Desktop and Network views (looks much nicer).
• Added option to trade rendering speed against visual quality.
• Can now load background images in PNG and JPG as well as GIF.
• Option to add simple graphical icons to Desktop and Network viewers.
• Added options to fade most viewlets to indicate their recent history (includes edges on a graph).
• Right-click context sensitive popup menu has been extended to provide fast access to common commands (eg. zoom, select etc...)
• Added FadeTable to quickly show activity of large 1D and 2D viewables.

• New Run-menu allows quick access to time profiler and port profiler
• Tested for compatibility up to Tcl/Tk 8.4.2

• outlining functions:
• hide/show all predicates/predicate/all clauses/clause/block
• go to previous/next heading / previous/next heading in same level  / up
• speedbar support, listing predicates and compiler directives
• indentation functions rewritten, to speed up indentation of regions

Embedding and Interfacing

Implemented a new protocol ("multitasking") which allows multiple ECLiPSe peers to become active quasi-simultaneously in response to certain events (e.g. breakpoints) in the ECLiPSe execution. See the documentation of peer_do_multitask/1, etc and the Java API documentation.

New low level embedding interface functionality:

• Waiting for an asynchronouly resumed ECLiPSe thread to return, with timeout: ec_wait_resume_status_long() in C interface, or ec_resume_status with optional timeout argument in Tcl.
• Test for variables: ec_is_var() in C, or EC_word::is_var() in C++.
• Comparing ECLiPSe terms: ec_compare() in C, or compare() in C++.

Kernel features

• All predicates that make nonlogical copies of terms (setval/getval, record/recorded, shelf_set/get, bag_enter/retrieve, store_set/get) now work with cyclic terms. Related new built-in:
• acyclic_term/1
• A new class of nonlogical storage, called stores. They are hash tables that can store arbitrary terms under arbitrary ground keys. A store is identified either by an anonymous handle or by a module-local name. New built-ins:
• current_store/1
• local store/1
• store_create/1
• store_count/2
• store_erase/1
• store_delete/1
• store_get/3
• store_inc/2
• store_set/3
• store_contains/3
• stored_keys/2
• stored_keys_and_values/3
• Domain declarations: the domain/1 declaration allows to define a mapping from symbols to natural numbers, similar to enumeration types in many programming languages. The definitions can be local or exported/imported. The new lib(ic_symbolic) is based on this facility.
• local domain/1, export domain/1
• current_domain/3
• domain_index/3
• New built-ins for date and time conversion:
• local_time/8 (conversion between local time and universal time and vice versa)
• local_time_string/3 (formatting time and date)
• The API for after-events has been made more comprehensive. New built-ins:
• cancel_after_event/2 (supersedes cancel_after_event/1)
• current_after_events/1 (supersedes current_after_event/2)
• event_after/3
• New external interface built-ins:
• peer_do_multitask/1
• peer_multitask_confirm/0
• peer_multitask_terminate/0
• peer_register_multitask/2
• The compiler now recognises
• discontiguous/1 (previously only in compatibility library)
• subscript/3 can be applied to byte strings and will extract the indexed byte
• string_code/3
• Other new built-ins:
• bag_count/2
• bag_erase/1
• current_struct/2 (supersedes current_struct/1)
• min/2 (minimum of a list)
• max/2 (maximum of a list)
• A deprecated-flag can be set for predicates. Use of such a predicate will trigger warnings during compilation.
• I/O output streams have a new property compress, which currently only affects the generation of EXDR 2 output. The default setting for this property is on for file, pipe and socket streams, and off for in-memory streams.
• I/O output streams have a new property last_written, whose value is the last character written to the stream.
• the -b command line option will now also load precompiled .eco files
• do-loops can be given a name (for debugging purposes) using the loop_name/1 specifier
• statistics/2 accepts event_time, which retrieves the timer used by after-events in a generic way
• new syntax:  property(functor) of ... expands into a name/arity specification of a declared structure.
• exit_block/1 accepts handles as arguments. This makes it easier to have unique exit tags.

Incompatibilities

• Compiler: initialization goals (:- local initialization(Goal)) are now executed only after the whole compilation unit has been compiled (compatible with ISO initialization directives)
• Arithmetic: breal_min/2, breal_max/2 and breal_bounds/3 work on any numeric argument type
• Events: new/modified events 75 (referring to a deprecated predicate), 96 (ambiguous import), 99 (unresolved ambiguous import),149 (code unit loaded), 166 (file successfully processed), 249 (debugger new suspensions event). The default handlers for events 68, 170, 191 now take 4 arguments.
• Modules: get_flag/3, is_predicate/1, is_built_in/1, is_dynamic/1 now fail silently when they refer to an ambiguously imported predicate. Previously, they raised warnings as well. Obsolete flags (protected,statistics) removed from get_flag/3. The flag enumeration order of get_flag/3 and pred/0 has changed.
• Memory: trimcore/0 now always includes a global stack garbage collection.
• Embedding and Interfacing: write_exdr/2 now generates the new, more compact EXDR version 2 format (see Embedding and Interfacing manual). read_exdr/2 can read both version 1 and version 2 formats.
• lib(scattered) is deprecated in favour of the discontiguous/1 directive which is now recognised directly by the compiler.
• lib(test_util): timeout/3 has been moved to lib(timeout). get_time/1 should be replaced with statistics(event_time,T).
• System calls: several builtins that map to Unix system calls (accept/3, cd/1, close/1, connect/2, select/3, wait/2) now get restarted automatically in case they were interrupted.
• lib(eplex): lp_var_get/3 now raises an error if information is not available because it was not requested at solver setup time. When a solution value gets rounded beyong the int_tolerance, a warning is printed.
• lib(eplex): with XPRESS-MP14, integer variables are restricted to a range of -2^31..2^31.

Previous release notes

• 5.5
• 5.4
• 5.3
• 5.2
• 5.1
• 5.0
• 4.2
• 4.1
• 4.0
• 3.6 and 3.7
• 3.5.2