substring

Usually defined for a single bit, mutation also acts at the substring level in the present application: with probability [p.sub.mut], a substring is picked and the corresponding attribute level within this substring is modified randomly.

--First, we do not cover other distance functions that do not fit the model of substring substitution.

Observe that the suffix tree of the new string is the same as that of the old string, since this alphabet mapping preserves the lexicographical ordering on substrings.

We write s = ~r to denote that string s has a substring that matches the PERL regular expression r.

The algorithm's feasibility was originally shown for the problem of computer virus detection in DOS environments [4] in which the protected data was DOS system files; the self set was generated by logically segmenting .com files into equal-size substrings of 32 (binary) characters; detectors (32-bit strings) were generated randomly; the r-contiguous-bits matching rule was used with thresholds ranging from 8 to 13 contiguous positions; and infections were generated by various file-infector viruses.

We refer to the technique of successively applying the leftmost longest-match rule, starting each time after the last character of the match, as "longest-match disjoint substring search." We say "disjoint" to indicate that the solutions may not overlap or nest.

The payload signature is a common substring in the payload of a packet.

So, considering single substring as the unique signature may not be invariant across worm instances.

The basic idea of the a mechanical sub-lexical: first create a thesaurus, give the string Chinese character word, cut the substring word in some way, continue cut the rest stars if the substring word match a dictionary word, otherwise the substring is not a word and re-cut to the Chinese character string to give the substring match.

If e is an inversion sequence, and ([e.sub.i]; [e.sub.i+1],[??] , [e.sub.j]) is a substring of e in which all positive entries are larger than k, then [[sigma].sub.-k] ([e.sub.i]; [e.sub.i+1],[??] , [e.sub.j]) is the sequence obtained by subtracting k from the positive entries of ([e.sub.i], [e.sub.i+1],[??] , [e.sub.j]).

Indeed, if f would be a substring of a vertex w that lies on [P.sub.1] (u), then since f starts with 0, only the bits left of this 0 would be changed.

Let [A.sub.1] be the substring x [1, i - 1], [A.sub.2] the substring x [i + 1, 2n- i], and [A.sub.3] the substring x [2n - i + 2, 2n].