Text messaging has long been a popular activity, and today smartphone apps enable users to choose from a plethora of mobile messaging applications. While we know a lot about SMS practices, we know less about practices of messaging applications. In this paper, we take a first step to explore one ubiquitous aspect of mobile messaging -- messaging history. We designed, built, and trialled a mobile messaging application without history named forget-me-not. The two-week trial showed that history-less messaging no longer supports chit-chat as seen in e.g. WhatsApp, but is still considered conversational and more 'engaging'. Participants expressed being lenient and relaxed about what they wrote. Removing the history allowed us to gain insights into what uses history has in other mobile messaging applications, such as planning events, allowing for distractions, and maintaining multiple conversation threads.

Box-bisection is a method for solving nonlinear systems. Space is subdivided into boxes of smaller and smaller diameter, and each subbox is tested for the existence of solutions by a test that either eliminates it from further consideration or marks it for subdivision. Simple bisection uses a test for the exclusion of subboxes, but no test that guarantees the existence of a unique solution in a subbox. Using this simple bisection, we show that the passed boxes tend to cluster in geometrical configura- tions whose number is stable under subdivision. This implies for many problems that the work required to do simple bisection may be prohibitive. However, improvements may be possible by grouping clusters and dynamically redefining the box proportions. The restriction to second-degree systems is sufficient to display this behavior.

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