  We present the Lightweight Parallel Foundations (LPF), an interoperable and
model-compliant communication layer adhering to a strict performance model of
parallel computations. LPF consists of twelve primitives, each with strict
performance guarantees, two of which enable interoperability.
  We argue that the principles of interoperability and model compliance suffice
for the practical use of immortal algorithms: algorithms that are proven
optimal once, and valid forever. These are ideally also implemented once, and
usable from a wide range of sequential and parallel environments. This paradigm
is evaluated by implementing an immortal fast Fourier transform (FFT) using
LPF, and compared to state-of-the-art FFT implementations. We find it performs
on par to Intel MKL FFT while consistently outperforming FFTW, thus showing
model compliance can be achieved without sacrificing performance.
  Interoperability encourages the propagation of immortal algorithms as widely
as possible. We evaluate this by integrating an LPF PageRank into Spark,
without changing any PageRank nor Spark source codes, and while requiring only
a minimal interface layer.
