The Vcsn team is happy to announce the long overdue release of Vcsn 2.6. Most of our work was devoted to providing a better, smoother, user experience. This includes improvements in the build system, better performances, extended consistency, and more legible error messages. Multitape expressions also received a lot of attention. For more information see the detailed news below. We warmly thank our users who made valuable feedback (read "bug reports") including Victor Miller, Dominique Soudière and Harald Schilly. Dominique and Harald helped integrating Vcsn into CoCalc (formerly SageMathCloud). People who contributed to this release: - Akim Demaille - Clément Démoulins - Clément Gillard - Sarasvati Moutoucomarapoulé Our next stop should be Vcsn 3.0, which will include extensive changes from Sarasvati. Release page: https://vcsn.lrde.epita.fr/Vcsn2.6 Tarball: https://www.lrde.epita.fr/dload/vcsn/2.6/vcsn-2.6.tar.bz2 Home page: https://vcsn.lrde.epita.fr The various packages (Docker, Debian, MacPorts, etc.) will appear soon. ## New features ### Promotion from single to multitape It is now possible to mix single-tape expressions with multitape expressions. This is especially handy when using labels classes (`[abc]`). For instance: In [2]: zmin2 = vcsn.context('lat<lan, lan>, zmin') In [3]: zmin2.expression(r'([ab] + ⟨1⟩(\e|[ab] + [ab]|\e))*') Out[3]: (a|a+b|b+<1>(\e|(a+b)+(a+b)|\e))* is a easy means to specify an expression generating an automaton that computes the edit-distance (between words or languages). Or, with a wide alphabet: In [4]: zmin = vcsn.context('lan(a-z), zmin') In [5]: zmin2 = zmin | zmin In [6]: zmin2 Out[6]: {abcdefghijklmnopqrstuvwxyz}? x {abcdefghijklmnopqrstuvwxyz}? -> Zmin In [7]: zmin2.expression(r'([^] + ⟨1⟩(\e|[^] + [^]|\e))*') In the future the display of expressions will also exploit this approach. ### vcsn compile now links with precompiled contexts If you write a program using dyn::, then it will benefit from all the precompiled algorithms. ### vcsn compile now supports --debug Use this to avoid the removal of intermediate object files. On some platforms, such as macOS, the object file contains the debug symbols, so their removal makes the use of a debug harder. ### vcsn compile now uses -rpath Programs/libraries generated by `vcsn compile` needed to be told where the Vcsn libraries were installed. In practice, it meant that `vcsn run` was needed to execute this program, and in some situations it was not even sufficient. Now, `vcsn compile my-prog.cc` generates `my-prog` which can be run directly. ### random_expression supports the tuple operator It is now possible to generate multitape expressions such as `(a|x*)*`. Before, random_expression was limited to expressions on multitape labels such as `(a|x)*`. In [1]: import vcsn In [2]: c = vcsn.context('lan(abc), q') In [3]: c2 = c | c In [4]: for i in range(10): ...: e = c2.random_expression('|, +, ., *=.2, w.=.2, w="min=-2, max=2"', length=10) ...: print('{:u}'.format(e)) ...: a|a+(ε|b)*+⟨1/2⟩ε|ε (ε+c)a|(⟨2⟩ε+c) (ε|b+(c|a)*)* ε|a+a|b c|b+⟨2⟩ε|(ε+b) ε|a+((a|ε)(ε|b)(ε|c))*(b|ε) (a|b+c|ε)(a|b) ε*|ε ε+a|a+⟨2⟩(b|ε) (ε+ε*)|ε Generating expressions with compose operators is also supported. In [5]: for i in range(10): ...: e = c2.random_expression('|=.5, +, ., @=2', length=10, identities='none') ...: print('{:u}'.format(e)) ...: ((b|ε)ε)(ε(ε|a)) ε(ε|c)+((ε|a)(a|b)+ε|c) ((ε|a)(ε|b))((b|a)(c|c)@b|b) (b|b@ε+a|b)@(c|ε@b|ε) (ε+ε|a)@(ε|c@ε|a+b|ε) (ε|a+ε|c)((ε|b)(c|ε)) (a|ε)((ε+c)|(a+ε)) c|ε@(a|ε)(ε|b@b|ε) (ε+ε|b)@ε|b+ε|a b(ε²)|((ε+ε)+a) ### New algorithms A few algorithms were added: - context.compose Composing `{abc} x {xyz}` with `{xyz} x {ABC}` gives, of course, `{abc} x {ABC}`. - expansion.normalize, expansion.determinize These are rather low-level features. The latter is used internally when derived-term is asked for a deterministic automaton. - expansion.expression The "projection" of an expansion as an expression. - label.compose For instance `a|b|x @ x|c` -> `a|b|c`. - polynomial.compose Additive extension of monomial composition. For instance composing `a|e|x + a|e|y + a|e|\e` with `x|E|A + y|E|A + \e|E|A` gives `<3>a|e|E|A`. - polynomial.shuffle and polynomial.infiltrate The missing siblings of polynomial.conjunction. ### Doxygen is no longer needed By default, `make install` generated and installed the C++ API documentation using Doxygen. It is now disabled by default, pass `--enable-doxygen` to `configure` to restore it. ## Bug Fixes ### Severe performance regression when reading daut Version 2.5 introduced a large penalty when reading daut files, especially large ones. ### Tupling of automata could be wrong on weights As a consequence, `expression.inductive` was also producing incorrect automata from multitape expressions. ### Polynomials featuring the zero-label Under some circumstances it was possible to have polynomials featuring monomials whose label is the zero of the labelset (e.g., `\z` with expressions as labels). This is fixed. ### Portability issues Newest compilers are now properly supported. ## Changes ### Divisions The division of expressions and automata now compute the product of the weights, not their quotient. ### Handling of the compose operator The support of the compose operators in expansions was completely rewritten. As a result, the derived-term automata are often much smaller, since many useless states (non coaccessible) are no longer generated. For instance the derived-term automaton of `(\e|a)* @ (aa|\e)*` has exactly two states. It used to have three additional useless states. ### Better diagnostics Many error messages have been improved. The Daut automaton format now treats `->` as a keyword, so `0->1 a` is now properly read instead of producing a weird error message because Vcsn thought your state was named `0->1`.