The aim of immediate constituent analysis (IC analysis) is to bring out the hierarchical structure in the composition of a complex sign. To this end, it is assumed that a complex sign is composed in a stepwise procedure which, at each step, applies an operator to an operand. In the simplest case, there is just one operand, and the operator is a segmental sign like the operand. In this case, a binary analysis is possible in which the complex at hand can be shown to be composed of two sequential parts. That is, at each step a complex is cut into two parts. This is a binary analysis.
All the parts of a whole brought out by this analysis are its constituents. At each level, a cut separates the immediate constituents of the complex. Cuts performed at the level of parts bring out mediate constituents of the whole.
Given a complex that consists of a sequence of constituents abcd, the first cut could, in principle, yield the immediate constituents a - bcd or ab - cd or abc -d. Only one of these binary analyses is correct. The method of making the cuts correctly involves testing the paradigmatic and the syntagmatic relations. Paradigmatic relations are tested by substitution tests; syntagmatic relations are tested by permutation tests.
Each x that is assumed to be a constituent is a member of a class – a grammatical category. At each level, the cut is performed in such a way that classes are maximized.
The correct IC analysis of German Ununterscheidbarkeit ‘indistinguishability’ is
Assume a sequence abc and let the question be whether constituency is [[ab][c]] or [[a][bc]]. This question may be answered by a permutation test as follows:
If there is a permutation cab, then the correct constituency is obviously the former, while if there is a permutation bca, then the correct constituency is the latter. This applies, for instance, to a complex sentence with a conjunction “in the middle”, like Linda worked while Irvin slept. This has a permutation while Irvin slept, Linda worked, showing that the conjunction is a constituent of the second clause.