The problem of searching through text to find a specified substring is considered in a practical setting. It is discovered that a method developed by Boyer and Moore can outperform even special-purpose search instructions that may be built into the computer hardware. For very short substrings however, these special purpose instructions are fastest-provided that they are used in an optimal way.

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A rype inclusion rest is a procedure io decide whether two type.~ are related by a giwn subtyping relationship. An efficient implementation of the rype inclu.~ion resr plays an important rote rn the perfonnance of object orienred programming languages wit.h mutr,iple subt.yping like C++. Eiffel or Java. There are well-known methods for performing fast consrnm rime type inclusion tesrs that use a hierarchical bit vector encoding of the partial ordered set representing the type hierarchy. The number of instructions required by t.hc type inclusion 1es1 rs proportional to the length of those bil vectors. We present a new algonthm based on graph coloring which computes a near optimal hierarchical encoding of type hierarchies. The. new algorithm improves significantly on previous results -i1 is faster, simpler and generates smaller bit vectors.

Earley's parsing algorithm is a general algorithm, able to handle any context-free grammar. As with most parsing algorithms, however, the presence of grammar rules having empty right-hand sides complicates matters. By analyzing why Earley's algorithm struggles with these grammar rules, we have devised a simple solution to the problem. Our empty-rule solution leads to a new type of finite automaton expressly suited for use in Earley parsers and to a new statement of Earley's algorithm. We show that this new form of Earley parser is much more time efficient in practice than the original.

The static single-assignment (SSA) form of a program provides data flow information in a form which makes some compiler optimizations easy to perform. In this paper we present a new, simple method for converting to SSA form, which produces correct solutions for nonreducible control-flow graphs, and produces minimal solutions for reducible ones. Our timing results show that, despite its simplicity, our algorithm is competitive with more established techniques.