Existing programs that find out words with same meanings I'm wondering if these 2 specific programs already exist and if not how hard would it be to write them:


A program that would figure out (by only "reading" large amounts of texts in human language 1 and 2) which words in second language have the same meaning as a word in first language.  You would give for input texts in both languages and for output you would get for every word in first language a list of words in second language that are most similar to it with a probability that they mean the same thing. 
A program that would figure out which words have the most similar meaning by analyzing large amounts of texts in one human language.


I'm planning on writing these two programs and it would be nice if I could get existing programs that do this so that I could compare results of my program to those of existing programs.
Let us simplify case 1 of the question: assume two files, first one with numbers written in indo-arabic numeral system (i.e. 123, 9, 186754, ...), second one in roman numeral system (XX, LCVI, IX, ...). How do you match pairs of symbols with same meaning ?

Without external information or assumptions, you can not. You could made the hypothesis that probability of one specific number is the same in both examples, and base your pairing on it. But then you need to find two input files that fulfills this condition.