I'm an author of multiple contributions accepted at the conference. Why do I have to pay a registration cost that is higher than the cost for just one registration?

Starting with MobileHCI 2022, full papers moved to a journal-based model where paper presentation at the conference is no longer required. While on the one hand, this gives more flexibility to authors, on the other hand, the potential drop in conference attendance connected with the adoption of this model can have an impact on the covering of the costs of publication.

Furthermore, please note that there are some fixed costs that need to be covered by the conference event in any case (e.g. room rental costs, provision of hybrid infrastructure). Registration fees, which represent the main income of the conference, are our primary source of income to cover such costs.

Other ACM / IEEE conferences, especially after COVID, have adopted a model that requires a unique author registration per paper (i.e. a full registration fee for each paper) e.g.:
https://2022.acmmm.org/registration/
https://2023.eurosys.org/registration.html
https://group.acm.org/conferences/group22/registration.php
https://ivaconference2022.ualg.pt/registration/

Therefore, with this model, author teams with an author whose name appears in two or more publications, need to pay multiple full-rate registrations to have their work presented. For MobileHCI 2023, we adopted a more flexible model, whereby an author included in multiple papers can present this work at MobileHCI, paying full-rate only for the first publication, and a significantly discounted rate for any subsequent publications.

The registration fee policy is going to cause problems for me.

Please email chair2023@mobilehci.acm.org so we can help work through possible issues on a case-by-case basis.

I'm only presenting a paper during a workshop. Do I need to pay the fee for the whole conference?

No. If a person plans to attend only a workshop (or only a tutorial), s/he has to pay just the workshop/tutorial fee, NOT the fee for the whole conference. To this regard, we provide a specific registration category for "Workshops/Tutorial Only" (see https://mobilehci.acm.org/2023/registration.php)

If multiple authors of a contribution that will be archived in the ACM DL Adjunct Proceedings (namely: Late Breaking Work, Demo, Industrial Perspectives, Doctoral Consortium, Workshop summary, Tutorial summary) are planning to attend, do all of them have to be registered prior to the deadline of August 25th to have their contributions appearing in the Adjunct Proceedings?

No, just one. Other authors can register whenever they like (including on-site).

I am a PhD student presenting my thesis during the Doctoral Consortium on the 28 of September. Do I have to register for the entire conference? Or can I register for just a single day?

You have to register for the full conference. However, please note that for students we provide discounted rates (see https://mobilehci.acm.org/2023/registration.php)

I am a PhD student but I'm not yet officially registered for the PhD school. Can I register with the student rate?

You should provide official documentation about your student status (i.e. student ID) to benefit from the student rate.

I'm going to remotely attend the conference. Why should I also pay the VAT (at the rate of 24%), differently from in-presence participants?

This is a requirement from the Greek legislation. Conference finances are managed by CONVIN, a local professional conference organizer, who is obliged to handle VAT according to a specific scheme which foresees that registrants need to pay the VAT only if they attend virtually.
However, the VAT should not burden much your registration costs, as fees for virtual registrations are lower than those for in-person attendees.

I have another question that you haven't answered, or I need clarification on my situation.

Please email chair2023@mobilehci.acm.org. We will also update this FAQ as people bring questions to us. Thank you for your understanding as we move forward and keep the MobileHCI 2023 conference series up and running!