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Documents authored by Mazorra, Bruno

Document
Extended Abstract
DOI: 10.4230/LIPIcs.AFT.2026.16
On Sybil-Proof Mechanisms (Extended Abstract)

Authors: Minghao Pan, Bruno Mazorra, Christoph Schlegel, and Akaki Mamageishvili

Published in: LIPIcs, Volume 395, 8th Conference on Advances in Financial Technologies (AFT 2026)

Abstract
We show that in the single-parameter mechanism design environment, the only non-wasteful, symmetric, incentive compatible and Sybil-proof direct mechanism is a second price auction with symmetric tie-breaking. Thus, if there is private information, lotteries or other mechanisms that do not always allocate to a highest-value bidder are not Sybil-proof or not incentive compatible. Moreover, we show that our main (im)possibility result extends beyond linear valuations, but not to multi-unit object allocation with unit-demand bidders. We also provide examples of mechanisms (with higher interim payoff for the bidders than a second price auction) that satisfy all of the other axioms and a weaker, Bayesian notion of Sybil-proofness. Thus, our (im)possibility result does not generalise to the Bayesian setting and we have a larger design space: With Sybil constraints, equivalence between dominant strategy and Bayesian implementation (that holds in classical single-parameter mechanism design without Sybils) no longer holds.
Cite as

Minghao Pan, Bruno Mazorra, Christoph Schlegel, and Akaki Mamageishvili. On Sybil-Proof Mechanisms (Extended Abstract). In 8th Conference on Advances in Financial Technologies (AFT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 395, pp. 16:1-16:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{pan_et_al:LIPIcs.AFT.2026.16,
  author =	{Pan, Minghao and Mazorra, Bruno and Schlegel, Christoph and Mamageishvili, Akaki},
  title =	{{On Sybil-Proof Mechanisms}},
  booktitle =	{8th Conference on Advances in Financial Technologies (AFT 2026)},
  pages =	{16:1--16:3},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-451-2},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{395},
  editor =	{Kiayias, Aggelos and Kyropoulou, Maria},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2026.16},
  URN =		{urn:nbn:de:0030-drops-278700},
  doi =		{10.4230/LIPIcs.AFT.2026.16},
  annote =	{Keywords: Sybils, Mechanism Design, Blockchain}
}
Document
DOI: 10.4230/LIPIcs.AFT.2026.19
Competing Auctions in Intermediated Markets

Authors: Bruno Mazorra, Minghao Pan, and Christoph Schlegel

Published in: LIPIcs, Volume 395, 8th Conference on Advances in Financial Technologies (AFT 2026)

Abstract
We analyze competing auctions in intermediated markets, where a seller selects among parallel mechanisms for the sale of a single good, most prominently the relay-and-protocol architecture of proposer-builder separation in Ethereum. When the intermediary can enforce single-homing on its bidders, sealed-bid second-price intermediary auctions fully unravel into the sealed first-price principal auction; open bidding-format intermediaries unravel only partially, collapsing into first-price in equilibrium under symmetric latency and sorting fast bidders to the intermediary under asymmetric latency. Any last-look advantage is removed through the availability of a credible sealed bidding channel. These results extend to multi-plexing environments (no enforcement by the intermediary). While the unraveling result indicates that the availability of a sealed first-price bidding channel pushes the overall market to the same auction structure, the very assumption of the credibility of such a channel is problematic, as the seller may have an incentive to leak information: a first-price auction is leakage-resistant in the presence of a single "fast" bidder but not against two or more. However, if the seller can credibly commit to not leak bids, it is optimal for them to do so. A main motivation is the forthcoming Glamsterdam update of Ethereum: our analysis suggests that the availability of an in-protocol (first-price) bidding channel severely limits the design space for out-of-protocol auctions by relays and other intermediaries.
Cite as

Bruno Mazorra, Minghao Pan, and Christoph Schlegel. Competing Auctions in Intermediated Markets. In 8th Conference on Advances in Financial Technologies (AFT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 395, pp. 19:1-19:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{mazorra_et_al:LIPIcs.AFT.2026.19,
  author =	{Mazorra, Bruno and Pan, Minghao and Schlegel, Christoph},
  title =	{{Competing Auctions in Intermediated Markets}},
  booktitle =	{8th Conference on Advances in Financial Technologies (AFT 2026)},
  pages =	{19:1--19:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-451-2},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{395},
  editor =	{Kiayias, Aggelos and Kyropoulou, Maria},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2026.19},
  URN =		{urn:nbn:de:0030-drops-278738},
  doi =		{10.4230/LIPIcs.AFT.2026.19},
  annote =	{Keywords: Competing auctions, proposer-builder separation, maximal extractable value}
}
Document
DOI: 10.4230/LIPIcs.AFT.2026.25
The Price of Decentralization in Block Building

Authors: Burak Öz, Fei Wu, Luis Correia, Sen Yang, Bruno Mazorra, and Stefanos Leonardos

Published in: LIPIcs, Volume 395, 8th Conference on Advances in Financial Technologies (AFT 2026)

Abstract
Decentralized block building mechanisms replace the monopoly of a single proposer with multiple builders. However, their censorship-resistance and fair-access benefits depend not only on the number of builders, but also on where builders are geographically positioned to provide transaction coverage. We study this tension between builder location choice, user transaction coverage, and utility concentration by modeling decentralized block building as a stochastic coverage game. Builders choose regions, information sources emit transactions over a block construction round, and latency determines whether a transaction is received before the deadline. We show that the game is an exact potential game and admits a pure Nash equilibrium. We prove an asymptotically tight factor-2 bound on the Price of Anarchy, which we interpret as the price of decentralization from uncoordinated builder placement. We also study builder utility concentration, showing that the lowest-utility builder earns at least half of the highest-utility builder’s payoff, and the utility-share HHI is at most 12.5% above the egalitarian benchmark. We complement the theory with simulations under richer latency and source environments and show that slot times, builder participation, and reward-sharing rules are important protocol design choices that can shape the price of decentralization.
Cite as

Burak Öz, Fei Wu, Luis Correia, Sen Yang, Bruno Mazorra, and Stefanos Leonardos. The Price of Decentralization in Block Building. In 8th Conference on Advances in Financial Technologies (AFT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 395, pp. 25:1-25:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{oz_et_al:LIPIcs.AFT.2026.25,
  author =	{\"{O}z, Burak and Wu, Fei and Correia, Luis and Yang, Sen and Mazorra, Bruno and Leonardos, Stefanos},
  title =	{{The Price of Decentralization in Block Building}},
  booktitle =	{8th Conference on Advances in Financial Technologies (AFT 2026)},
  pages =	{25:1--25:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-451-2},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{395},
  editor =	{Kiayias, Aggelos and Kyropoulou, Maria},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2026.25},
  URN =		{urn:nbn:de:0030-drops-278791},
  doi =		{10.4230/LIPIcs.AFT.2026.25},
  annote =	{Keywords: decentralization, block building, potential game, price of anarchy}
}

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