By performing certain state rites performed by these predecessors-as most notably in the Inauguration ceremonies-they effectively make this connection. American presidents need not rely solely on verbal reminders, citing Washington, Jefferson, Lincoln, and Roosevelt in their speeches. New leaders do all they can to identify themselves with popular predecessors.
It is through symbolic expressions, including rituals, that leaders link the state today to its earlier incarnations, and likewise link both themselves and their enemies to particular predecessors, viewed in certain ways. Kertzer, in International Encyclopedia of the Social & Behavioral Sciences, 2001 2.4 The Uses of HistoryĪ common feature of representations of the state is that they contain an image of history. On the other hand, it develops general approaches and algorithms that apply to whole classes of theories.ĭ.I. Research on equational unification is, on the one hand, interested in classifying equational theories of interest according to their behavior in this respect. E-unifiability may be undecidable, and even if it is decidable, solvable unification problems need not have a most general. In fact, depending on the theory E in question. For equational unification, things are not as nice as for syntactic unification. This substitution is denoted as σ :=, we have f( x, a) σ = f( a, a) = E g( a, a) = g( a, x) σ, where = E denotes the equational theory induced by E. In this example, if we substitute b for x and a for y, we obtain the unified term f( a, b). The unification problem for the terms s = f( a, x) and t = f( y, b) is concerned with the following question: is it possible to replace the variables x, y in s and t by terms such that the two terms obtained this way are (syntactically) equal. To be more concrete, one usually considers terms that are built from function symbols (say f, a, and b, where f is binary and a, b are nullary) and variable symbols (say x and y). Very generally speaking, unification tries to identify two symbolic expressions by replacing certain sub-expressions (variables) by other expressions.
Klaus Schulz, in Handbook of Automated Reasoning, 2001 1.1 What is unification?