A library object is used to modify an entire fragment by using a pre-defined database, or library. That pre-defined database consist of a set of files, all formatted the same way, and each describing a possible structure for that fragment. One can seek models for large molecules by first constructing libraries for different fragments of the entire structure. Those libraries can be efficiently built by using MCSYM independently on each fragments.
The main objective behind the creation of the library object is quite similar to that of the cache object: we wanted to save the exponential processing time lost when generating more than once the same sub-structures on different edges of the backtrack tree.
For optimisation purposes, the algorithm assumes that all files of the same library are formatted exactly the same way (the first file in the set is used as a reference for the entire library. This means that residues must be defined in the same order in every file.
Before using a library object, one must specify the files constituting the library. For now, only three type of files are available: the PDB format, the binary format and through socket. All input files must be named exactly the same way, i.e. <name><number><suffix>; the number must be encoded in a C format. File numbers must begin at 1 and must be consecutive.
Example:
anticodon-00001.pdb.gz anticodon-00002.pdb.gz anticodon-00003.pdb.gz anticodon-00004.pdb.gz ...