johnny decimal system

the johnny decimal system¹ is meant as an approach to store information based on the dewey decimal system using decimalized numbering.

the idea is to force a shallow file structure by having your entire set of files, $S$ in maximally ten super-groups with ten subjects in each super-group, which is then finally subdivided into ten subgroups². conceptually, i think it makes the most sense to look at as a tensor:

$$S=\left\{\begin{array}{c}\text{admin super-group 00-09: }\left[\begin{array}{c}\text{admin group 00:}\left(\begin{array}{c}\text{admin-admin subject 00.00}\\ \text{admin subject 00.01}\\ ⋮\\ \text{admin subject 00.09}\end{array}\right)\\ \\ \text{group 01:}\left(\begin{array}{c}\text{admin subject 01.00}\\ \text{subject 01.01}\\ ⋮\\ \text{subject 01.09}\end{array}\right)\\ \\ ⋮\\ \\ \text{group 09}\left(\begin{array}{c}\text{admin subject 09.00}\\ \text{subject 09.01}\\ ⋮\\ \text{subject 09.09}\end{array}\right)\end{array}\right]\\ \\ \text{super-group 10-19: }\left[\begin{array}{c}\text{admin group 10:}\left(\begin{array}{c}\text{admin-admin subject 10.00}\\ \text{admin subject 10.01}\\ ⋮\\ \text{admin subject 10.09}\end{array}\right)\\ \\ \text{group 11:}\left(\begin{array}{c}\text{admin subject 11.00}\\ \text{subject 11.01}\\ ⋮\\ \text{subject 11.09}\end{array}\right)\\ \\ ⋮\\ \\ \text{group 19}\left(\begin{array}{c}\text{admin subject 19.00}\\ \text{subject 19.01}\\ ⋮\\ \text{subject 19.09}\end{array}\right)\end{array}\right]\\ \\ \\ ⋮\\ \\ \text{super-group 90-99: }\left[\begin{array}{c}\text{admin group 90:}\left(\begin{array}{c}\text{admin-admin subject 90.00}\\ \text{admin subject 90.01}\\ ⋮\\ \text{admin subject 90.09}\end{array}\right)\\ \\ \text{group 91:}\left(\begin{array}{c}\text{admin subject 91.00}\\ \text{subject 91.01}\\ ⋮\\ \text{subject 91.09}\end{array}\right)\\ \\ ⋮\\ \\ \text{group 99}\left(\begin{array}{c}\text{admin subject 99.00}\\ \text{subject 99.01}\\ ⋮\\ \text{subject 99.09}\end{array}\right)\end{array}\right]\end{array}\right\}$$

the idea is of course that the folder count can be changed as needed, but that you are forced to secure a shallow file tree. nothing stops you from using for other systems.

the main disadvantage of using such a system (outside of initial time cost of making your index) is the lack of ability to store multi-category items. we, as humans, have a bad tendency to put things in boxes that defy such an inherent act of violence. so how do you solve that? as always, public voit has the answer: tagging.

Footnotes

1. the “Johnny.Decimal system” is licensed under Attribution-NonCommercial-ShareAlike 4.0 International on their website’s license page ↩

2. the numbers 00-09 are reserved for managing the system itself ↩