From open resources to educational opportunity

Since MIT’s bold announcement of the OpenCourseWare initiative in 2001, the content of over 700 of its courses have been published on the Web and made available for free to the world. Important infrastructure initiatives have also been launched recently with a view to enabling the sustainable implementation of these educational programmes, through strengthening organizational capacity as well as through building open, standards‐based technology. Each of these initiatives point to a rich palette of transformational possibilities for education; together with the growing open source movement, they offer glimpses of a sustainable ecology of substantial and quality educational resources. This discussion piece will highlight some of the educational opportunity presented by MIT’s current information technology‐enabled educational agenda and related initiatives, along with their strategic underpinnings and implications. It will address various dimensions of their impact on the form and function of education. It will examine how these ambitious programmes achieve a vision characterized by an abundance of sustainable, transformative educational opportunities, not merely pervasive technology

An Alternate Construction of an Access-Optimal Regenerating Code with Optimal Sub-Packetization Level

Given the scale of today's distributed storage systems, the failure of an individual node is a common phenomenon. Various metrics have been proposed to measure the efficacy of the repair of a failed node, such as the amount of data download needed to repair (also known as the repair bandwidth), the amount of data accessed at the helper nodes, and the number of helper nodes contacted. Clearly, the amount of data accessed can never be smaller than the repair bandwidth. In the case of a help-by-transfer code, the amount of data accessed is equal to the repair bandwidth. It follows that a help-by-transfer code possessing optimal repair bandwidth is access optimal. The focus of the present paper is on help-by-transfer codes that employ minimum possible bandwidth to repair the systematic nodes and are thus access optimal for the repair of a systematic node. The zigzag construction by Tamo et al. in which both systematic and parity nodes are repaired is access optimal. But the sub-packetization level required is $r^k$ where $r$ is the number of parities and $k$ is the number of systematic nodes. To date, the best known achievable sub-packetization level for access-optimal codes is $r^{k/r}$ in a MISER-code-based construction by Cadambe et al. in which only the systematic nodes are repaired and where the location of symbols transmitted by a helper node depends only on the failed node and is the same for all helper nodes. Under this set-up, it turns out that this sub-packetization level cannot be improved upon. In the present paper, we present an alternate construction under the same setup, of an access-optimal code repairing systematic nodes, that is inspired by the zigzag code construction and that also achieves a sub-packetization level of $r^{k/r}$.Comment: To appear in National Conference on Communications 201