The Johnson-Lindenstrauss lemma shows that a set of n points in high dimensional Euclidean space can be mapped down into an O(log n=ffl 2 ) dimensional Euclidean space such that the distance between any two points changes by only a factor of (1 Σ ffl). In this note, we prove this lemma using elementary probabilistic techniques. Computer Science Division, UC Berkeley. Email: dasgupta@cs.berkeley.edu. y Computer Science Division, UC Berkeley. Email: angup@cs.berkeley.edu. Supported by...