With the impending implementation of Firebird as a backend for LibreOffice Base, to replace HSQLDB, I re-ran the tests of converging and cyclic cascades that were previously carried out for other databases. These tests were carried out using Firebird 2.5 running on Ubuntu Server 12.04.2 (64 bit), and using FlameRobin 0.9.3.2220 Unicode running on Ubuntu 13.04 (64 bit).
The only revision to the previous code was the elimination of the "null" specification for the element column of the d_sample table.
All of the tests of converging and cyclic cascades were completed successfully with Firebird. Firebird therefore joins PostgreSQL and SQLite among the DBMSs that are feasible options for implementing complex data structures.