In spectral graph theory a graph with least eigenvalue −2 is exceptional if it is connected, has least eigenvalue greater than or equal to −2, and it is not a generalized line graph. A (κ, τ)-regular set S of a graph is a vertex subset, inducing a κ-regular subgraph such that every vertex not in S has τ neighbors in S. We present a recursive construction of all regular exceptional graphs as successive extensions by regular sets.

On the wings of New Public Management (NPM) and the Bologna Process, Higher Education Institutions (HEI) needed to innovate towards market orientation, both students demanding and social relevance. One way to achieve these objectives is through co-creation processes, involving students and partners outside as companies and public institutions. The purpose of this paper is to assess the satisfaction of Instituto Politécnico de Bragança (IPB) students who actively participated in a co-creation process called Demola, which aims the pedagogical innovation and strengthening the link with and the community. Quantitative data was collected through an online survey that included questions about students' perception on the impact of the co-creation process Demola. The population is 250 students who participated in eight batches in the last four years, working in 44 co-creation cases or challenges. 87 students answered the questionnaire, corresponding to 34,8% of the sample. Main results and conclusions suggested high levels of satisfaction among IPB students’ and are perceived as having very positive impact in skills’ development.