标签: binary search

I recently read an article about something called the EyeWriter Project . This involves an international team that is working together to create a low-cost, open source eye-tracking system that will allow Amyotrophic Lateral Sclerosis (ALS) patients to draw using just their eyes ( Click here to see the full article). This is something that is close to my heart, because one of my very dear friends, Steve Pesto, was a victim of ALS – he shrugged off this mortal coil several years ago now. As an aside, you might be interested in Steve's last joke on me. Throughout most of the year (Spring, Summer, Fall), I am well known for wearing nothing but shorts and Hawaiian shirts – generally speaking I wear the same clothes for home, the office, church, and parties. Of course there are always exceptions to every rule. Thus it was that on the occasion of Steve's funeral I dusted off my black suit and tie (the one I keep for emergencies) and headed off to the ceremony. You can only imagine my surprise when I entered the church and discovered that everyone else was dressed in their brightest, most colourful garments, including many Hawaiian shirts. It seems that Steve had requested that everyone attending the funeral wore their "brightest and best" ... but somehow he and his wife had "neglected" to let me know about this plan. The end result was that the person who never wears a suit was the only person in one, whilst everyone else was sporting my usual attire. As I sat through the ceremony, I could imagine Steve looking at me with his expressive eyes (the only thing he could still move towards the end) twinkling at me. But we digress, one of the things that Steve introduced me to was the Dasher Project ( Click here for more details). This is an information-efficient text-entry interface for wherever a full-size keyboard cannot be used – for example, when operating a computer without using one's hands (this is, by head-mouse or by eye-tracker). For the final year or so, Steve largely communicated by means an eye-tracking camera mounted on top of a notebook computer attached to his wheelchair. Using the camera and Dasher software, Steve could build up words and sentences, which could subsequently be emailed or passed to a speech synthesiser. But sometimes Steve was too fatigued even for this. This is why Steve invented something he called his "Letter Board". This was a sheet of paper, on one side of which was a coloured binary-tree type diagram as shown below:   Steve Pesto's Letter Board   Being an engineer, Steve had based this board on a binary search algorithm that achieves optimum efficiency by utilising the frequency of occurrence of letters in the English language. Assuming the disable person has any motion at all (Steve could blink once for Yes, while the absence of a blink meant No), Steve's letter-board can be used with the caregiver just pointing to letters starting with the most frequently used letters which are at the top. An even more efficient way to use this tool is for the caregiver to call out colours, and then light or dark, and then left or right, and so on. As you may notice, one of the options on this sheet says to "Turn Over" . Printed on the back is another colour-coded binary tree in textual form covering common requirements like adjusting various portions of the body to relieve pain, required medications, and so forth. After you have experimented with this tool for a few minutes, you come to realise just how much thought went into it and also how incredibly useful it can be. Steve really wanted to make his Letter Board available for anyone else to use, so you can Click here to download a compressed ZIP file containing a PDF, which you can print out directly. Also, the ZIP file contains an Excel version that you can customise along with a Word document containing the questions that you print on the back of the Letter Board (which you can also customise). Please pass this information on to anyone you know who is disabled (or to their caregivers).