<Li> Functional specification <Ul> <Li> specify a system as a structure of mathematical functions </Li> <Li> OBJ, ASL, PLUSS, LARCH, HOL or PVS rely on this paradigm </Li> </Ul> </Li> <Ul> <Li> specify a system as a structure of mathematical functions </Li> <Li> OBJ, ASL, PLUSS, LARCH, HOL or PVS rely on this paradigm </Li> </Ul> <Li> specify a system as a structure of mathematical functions </Li> <Li> OBJ, ASL, PLUSS, LARCH, HOL or PVS rely on this paradigm </Li>

What was one specification that was a challenge to understand