This page is intended as a relatively technical log of changes to the LKB source code, in a sense a condensed summary of the CVS revision history. LKB developers will likely find this information most interesting, but it may also help some users to stay up-to-date on latest LKB development. For a more high-level summary of changes to LKB functionality and additions of new facilities, see LkbUpdates instead.

Please note that some of the LKB variables and functions mentioned in these development logs refer to LKB internals and might change in future versions; documentation of new or experimental facilities here is primarily targetting LKB developers (or system integrators), thus it seems important to maintain a conceptual distinction between the `official' LKB interface (e.g. what is documented in Copestake, 2002, plus updates on, say, the LkbUpdates page) and system internals.

Portability::

• to allow compilation on SBCL (a variant of CMUCL that apears to be very actively developed currently and is available for many platforms, including

  Linux on PPC and MacOS X) i had to rename the LKB structure type to ltype. this change is trivial in nature but affects a large number of source files; it is possible that i introduced errors as i worked through the renaming. furthermore, i moved to the latest versions of PPCRE (the regular expression library) and the defsystem() facility; i can now compile and run on SBCL on Linux (x86.32).

Selective Unpacking::

• the unpacking code has moved into a new file main/unpack.lsp, the (unused) id argument to unpack-edge!() et al. has been deleted, and a new selective unpacking mode added: selectively-unpack-edges() searches for the n best consistent results (as determined by a Redwoods-style ME model) without exploring the complete forest; generate-from-mrs() takes a new nanalyses keyword argument to enable selective unpacking.

64-Bit Support::

• to add support for 64-bit Linux (on AMD64 and EM64T), all binary directories

  formerly called linux have been broken up into linux.x86.32 and linux.x86.64; a small number of code changes was required to add support for the (new) Allegro CL 7.0 and allow the LKB to run in true 64-bit mode; the PVM et al. binaries and .so files bundled with [incr tsdb()] have been recompiled against PVM 3.4.5 and are included in the distribution in both a 32-bit and 64-bit version each.

Redwoods-Style MRS Banking::

• discriminant extraction, storage in [incr tsdb()], and the CLIM and HTML UIs now support comparison and annotation of sets of MRSs; discriminants in this mode are triples extraced from the (handle-free) elementary dependency view

  on MRSs, either of the form (predicate, role, predicate) or (predicate, property, value), where the latter form implicitly assumes that the specific property occurs in the ARG0 of the first predicate. to make multiple occurences of the same predicate unique, it is necessary to have a way of `anchoring' each EP to a part of the original input: for the time being, MRS banking depends on the availability of a new LNK property in EPs (see below).

Generation from Fragmented MRSs::

• in LOGON, there is a notion of `fragmented' MRSs, i.e. a single MRS that corresponds to a sequence of MRSs associated to a sequence of chunks found by the (XLE) parser in robust mode; while each fragment is expected to be semantically well-formed, the individual pieces are connected by virtue of a

  fragment_rel that can be viewed as a highly underspecified conjunction, i.e. uses roles L-HNDL, L-INDEX, R-HNDL, and R-INDEX to encode a binary tree. generation from fragmented MRSs is triggered by fragmentp() of the input MRS to generation, then aims to extract connected fragments, generate from each individually, and cross-multiply the resulting strings. new variables: *semi-fragment-relations* and *fragment-start-symbols*.

Discovery of Orthographic Variants::

• there is new code to compile a file in the format of variants.tab as it is part of recent versions of the ERG. essentially, the code looks for sets of lexical entries that are equivalent modulo STEM and ONSET and outputs an ordered list of (identifiers of) such lexical entries, with the additional information of whether or not they occur in *duplicate-lex-ids* (the ones following the colon in variants.tab), i.e. are disabled for generation. new variable: *orthographic-variants* (a hash table relating such sets); new functions: find-orthographic-variants() and orthographic-variants-p().

MRS Internals::

• the scratch slot has been removed from the psoa structure (it was unused, and the transfer component which had originally introduced it no longer has a need for it). a new link slot was added to the rel structure, jointly with support in the MRS reader and printer(s) to support a LNK property on EPs, viz. a list of (token) identifiers corresponding to this bit of MRS. the idea is the same as with characterization' (i.e. the CFROM and CTO` properties on EPs), but in some set-ups (i.e. the XLE, VerbMobil, YY) there is no way of obtaining (or defining) character positions; new variable: *rel-link-feature*. other minor changes to MRS internals include a new variable *mrs-equalp-ignored-roles* to further parameterize mrs-equalp() (i.e. allow an application to specify a set of roles to be ignored for the test) and a means of color-coding individual EPs in MRS HTML output, see changes in basemrs.lisp and interface.lisp.

Minor LKB-Internal Changes::

• the edge structure now has an additional slot string to allow recording the surface form associated to an edge explicitly, i.e. on generator outputs. the cache in unpack-edge()! has been simplified to no longer incur each unpacking failure (which was done exclusively for accounting purposes) for each context that embeds an edge; the effect is that some of the problematic items in generation from the new Rondane corpus no longer cause apparent non-termination in upacking (viz. where there are huge numbers of globally inconsistent hypothesis in the forest as a result of the latest ERG move to restrict the syntactic information associated to punctuation).

[incr tsdb()] Functionality::

• for PVM communication, a new variable *pvm-encoding* or additional slot encoding on cpu definitions can be used to force a certain encoding for [incr tsdb()] to client communication; for backwards compatibility, the default is nil, in which case the encoding continues to be determined by arbitrary environment factors, e.g. value of LANG and -locale option on Lisp start-up. furthermore, there is emerging support for an alternative Redwoods update mode, looking for an exact match to the `gold' target rather than using discriminants; also, the stochastic experimentation tools have been significantly extended to support scripting of series of experiments and the type of set-up documented in the TLT04 paper (see redwoods.lisp and maxent.lisp).

Extension of Transfer Engine::

• the MRS rewrite engine has seen a couple of bug fixes and extensions that are

  all backwards-compatible (e.g. the addition of EQUAL and SUBSUME flags) since its last release from the LOGON source code repository. while this add-on component is still exclusively used within LOGON, hope that there will be separate documentation at some point.