Les Jones

Word of the Day > WOTD: Dichotomous Key

From Wikipedia:

In Biology. a single-access key (also called "sequential key", "analytical key", or "pathway key") is an identification key where the sequence and structure of identification steps is fixed by the author of the key. At each point in the key multiple options are offered, each option leading to the next choice. The options are commonly called "leads", the set of leads at a given point a "couplet". If the entire key consists of exactly two choices at each branching point, the key is called dichotomous, else polytomous (or in false analogy: "polychotomous"). The majority of single-access keys are dichotomous.

I know all about dichotomous keys from my mis-spent youth getting a biology degree. In field biology dichotomous keys are used to identify the flora and fauna of a given geographic region. As long as you understand the terminology the key will walk you through a step-by-step identification process.

Nowadays you see the same idea used in other applications. For instance (and this is what inspired this post), go here and click the "Begin Here" link. That page is a dichotomous key to identifying Mosin-Nagant rifles. If I ever buy a Mosin I'll make a beeline for that page. Good stuff.

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