1. A method of identifying molecules represented by concatenated strings, said method comprising: i) providing a collection of two or more different initial character strings representing two or more initial biological molecules into a computer system associated with a synthesis machine; ii) using the computer system, selecting at least two substrings from said collection of the two or more different initial character strings; iii) using the computer system, concatenating the at least two selected substrings to form product strings; iv) using the computer system, selecting one or more product biological molecules for synthesis, wherein the one or more product biological molecules are represented by one or more of the product strings; and v) synthesizing the one or more product biological molecules using the synthetic machinery.