@article{PanhansSchumacher2021, author = {Panhans, Matthew T. and Schumacher, Reinhard}, title = {Theory in closer contact with industrial life}, series = {Journal of institutional economics}, volume = {17}, journal = {Journal of institutional economics}, number = {5}, publisher = {Cambridge Univ. Press}, address = {Cambridge}, issn = {1744-1374}, doi = {10.1017/S1744137421000357}, pages = {781 -- 798}, year = {2021}, abstract = {This paper investigates the views on competition theory and policy of the American institutional economists during the first half of the 20th century. These perspectives contrasted with those of contemporary neoclassical and later mainstream economic approaches. We identify three distinct dimensions to an institutionalist perspective on competition. First, institutionalist approaches focused on describing industry details, so as to bring theory into closer contact with reality. Second, institutionalists emphasized that while competition was sometimes beneficial, it could also be disruptive. Third, institutionalists had a broad view of the objectives of competition policy that extended beyond effects on consumer welfare. Consequently, institutionalists advocated for a wide range of policies to enhance competition, including industrial self-regulation, broad stakeholder representation within corporations, and direct governmental regulations. Their experimental attitude implied that policy would always be evolving, and antitrust enforcement might be only one stage in the development toward a regime of industrial regulation.}, language = {en} } @article{KastiusSchlosser2022, author = {Kastius, Alexander and Schlosser, Rainer}, title = {Dynamic pricing under competition using reinforcement learning}, series = {Journal of revenue and pricing management}, volume = {21}, journal = {Journal of revenue and pricing management}, number = {1}, publisher = {Springer Nature Switzerland AG}, address = {Cham}, issn = {1476-6930}, doi = {10.1057/s41272-021-00285-3}, pages = {50 -- 63}, year = {2022}, abstract = {Dynamic pricing is considered a possibility to gain an advantage over competitors in modern online markets. The past advancements in Reinforcement Learning (RL) provided more capable algorithms that can be used to solve pricing problems. In this paper, we study the performance of Deep Q-Networks (DQN) and Soft Actor Critic (SAC) in different market models. We consider tractable duopoly settings, where optimal solutions derived by dynamic programming techniques can be used for verification, as well as oligopoly settings, which are usually intractable due to the curse of dimensionality. We find that both algorithms provide reasonable results, while SAC performs better than DQN. Moreover, we show that under certain conditions, RL algorithms can be forced into collusion by their competitors without direct communication.}, language = {en} } @inproceedings{SchlosserBoissier2017, author = {Schlosser, Rainer and Boissier, Martin}, title = {Optimal price reaction strategies in the presence of active and passive competitors}, series = {Proceedings of the 6th International Conference on Operations Research and Enterprise Systems - ICORES}, booktitle = {Proceedings of the 6th International Conference on Operations Research and Enterprise Systems - ICORES}, editor = {Liberatore, Federico and Parlier, Greg H. and Demange, Marc}, publisher = {SCITEPRESS - Science and Technology Publications, Lda.}, address = {Set{\´u}bal}, isbn = {978-989-758-218-9}, doi = {10.5220/0006118200470056}, pages = {47 -- 56}, year = {2017}, abstract = {Many markets are characterized by pricing competition. Typically, competitors are involved that adjust their prices in response to other competitors with different frequencies. We analyze stochastic dynamic pricing models under competition for the sale of durable goods. Given a competitor's pricing strategy, we show how to derive optimal response strategies that take the anticipated competitor's price adjustments into account. We study resulting price cycles and the associated expected long-term profits. We show that reaction frequencies have a major impact on a strategy's performance. In order not to act predictable our model also allows to include randomized reaction times. Additionally, we study to which extent optimal response strategies of active competitors are affected by additional passive competitors that use constant prices. It turns out that optimized feedback strategies effectively avoid a decline in price. They help to gain profits, especially, when aggressive competitor s are involved.}, language = {en} } @article{QuintanaArimBadosaetal.2015, author = {Quintana, Xavier D. and Arim, Matias and Badosa, Anna and Maria Blanco, Jose and Boix, Dani and Brucet, Sandra and Compte, Jordi and Egozcue, Juan J. and de Eyto, Elvira and Gaedke, Ursula and Gascon, Stephanie and Gil de Sola, Luis and Irvine, Kenneth and Jeppesen, Erik and Lauridsen, Torben L. and Lopez-Flores, Rocio and Mehner, Thomas and Romo, Susana and Sondergaard, Martin}, title = {Predation and competition effects on the size diversity of aquatic communities}, series = {Aquatic sciences : research across boundaries}, volume = {77}, journal = {Aquatic sciences : research across boundaries}, number = {1}, publisher = {Springer}, address = {Basel}, issn = {1015-1621}, doi = {10.1007/s00027-014-0368-1}, pages = {45 -- 57}, year = {2015}, abstract = {Body size has been widely recognised as a key factor determining community structure in ecosystems. We analysed size diversity patterns of phytoplankton, zooplankton and fish assemblages in 13 data sets from freshwater and marine sites with the aim to assess whether there is a general trend in the effect of predation and resource competition on body size distribution across a wide range of aquatic ecosystems. We used size diversity as a measure of the shape of size distribution. Size diversity was computed based on the Shannon-Wiener diversity expression, adapted to a continuous variable, i.e. as body size. Our results show that greater predation pressure was associated with reduced size diversity of prey at all trophic levels. In contrast, competition effects depended on the trophic level considered. At upper trophic levels (zooplankton and fish), size distributions were more diverse when potential resource availability was low, suggesting that competitive interactions for resources promote diversification of aquatic communities by size. This pattern was not found for phytoplankton size distributions where size diversity mostly increased with low zooplankton grazing and increasing nutrient availability. Relationships we found were weak, indicating that predation and competition are not the only determinants of size distribution. Our results suggest that predation pressure leads to accumulation of organisms in the less predated sizes, while resource competition tends to favour a wider size distribution.}, language = {en} } @article{CaronDeFrenneBrunetetal.2015, author = {Caron, Maria Mercedes and De Frenne, Pieter and Brunet, J{\"o}rg and Chabrerie, Olivier and Cousins, Sara A. O. and Decocq, Guillaume and Diekmann, Martin and Graae, Bente Jessen and Heinken, Thilo and Kolb, Annette and Lenoir, Jonathan and Naaf, Tobias and Plue, Jan and Selvi, Federico and Wulf, Monika and Verheyen, Kris}, title = {Divergent regeneration responses of two closely related tree species to direct abiotic and indirect biotic effects of climate change}, series = {Forest ecology and management}, volume = {342}, journal = {Forest ecology and management}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0378-1127}, doi = {10.1016/j.foreco.2015.01.003}, pages = {21 -- 29}, year = {2015}, abstract = {Changing temperature and precipitation can strongly influence plant reproduction. However, also biotic interactions might indirectly affect the reproduction and recruitment success of plants in the context of climate change. Information about the interactive effects of changes in abiotic and biotic factors is essential, but still largely lacking, to better understand the potential effects of a changing climate on plant populations. Here we analyze the regeneration from seeds of Acer platanoides and Acer pseudoplatanus, two currently secondary forest tree species from seven regions along a 2200 km-wide latitudinal gradient in Europe. We assessed the germination, seedling survival and growth during two years in a common garden experiment where temperature, precipitation and competition with the understory vegetation were manipulated. A. platanoides was more sensitive to changes in biotic conditions while A. pseudoplatanus was affected by both abiotic and biotic changes. In general, competition reduced (in A. platanoides) and warming enhanced (in A. pseudoplatanus) germination and survival, respectively. Reduced competition strongly increased the growth of A. platanoides seedlings. Seedling responses were independent of the conditions experienced by the mother tree during seed production and maturation. Our results indicate that, due to the negative effects of competition on the regeneration of A. platanoides, it is likely that under stronger competition (projected under future climatic conditions) this species will be negatively affected in terms of germination, survival and seedling biomass. Climate-change experiments including both abiotic and biotic factors constitute a key step forward to better understand the response of tree species' regeneration to climate change. (C) 2015 Elsevier B.V. All rights reserved.}, language = {en} } @article{LeifsoMacDougallHusbandetal.2012, author = {Leifso, A. and MacDougall, A. S. and Husband, B. and Hierro, J. L. and K{\"o}chy, Martin and P{\"a}rtel, M. and Peltzer, D. A.}, title = {Expansion of a globally pervasive grass occurs without substantial trait differences between home and away populations}, series = {Oecologia}, volume = {170}, journal = {Oecologia}, number = {4}, publisher = {Springer}, address = {New York}, issn = {0029-8549}, doi = {10.1007/s00442-012-2370-4}, pages = {1123 -- 1132}, year = {2012}, abstract = {The global expansion of species beyond their ancestral ranges can derive from mechanisms that are trait-based (e.g., post-establishment evolved differences compared to home populations) or circumstantial (e.g., propagule pressure, with no trait-based differences). These mechanisms can be difficult to distinguish following establishment, but each makes unique predictions regarding trait similarity between ancestral ('home') and introduced ('away') populations. Here, we tested for trait-based population differences across four continents for the globally distributed grass Dactylis glomerata, to assess the possible role of trait evolution in its worldwide expansion. We used a common-environment glasshouse experiment to quantify trait differences among home and away populations, and the potential relevance of these differences for competitive interactions. Few significant trait differences were found among continents, suggesting minimal change during global expansion. All populations were polyploids, with similar foliar carbon:nitrogen ratios (a proxy for defense), chlorophyll content, and biomass. Emergence time and growth rate favored home populations, resulting in their competitive superiority over away populations. Small but significant trait differences among away populations suggest different introductory histories or local adaptive responses following establishment. In summary, the worldwide distribution of this species appears to have arisen from its pre-adapted traits promoting growth, and its repeated introduction with cultivation and intense propagule pressure. Global expansion can thus occur without substantial shifts in growth, reproduction, or defense. Rather than focusing strictly on the invader, invasion success may also derive from the traits found (or lacking) in the recipient community and from environmental context including human disturbance.}, language = {en} } @article{NottebrockEslerSchurr2013, author = {Nottebrock, Henning and Esler, Karen J. and Schurr, Frank Martin}, title = {Effects of intraspecific and community density on the lifetime fecundity of long-lived shrubs}, series = {Perspectives in plant ecology, evolution and systematics}, volume = {15}, journal = {Perspectives in plant ecology, evolution and systematics}, number = {3}, publisher = {Elsevier}, address = {Jena}, issn = {1433-8319}, doi = {10.1016/j.ppees.2013.03.003}, pages = {150 -- 161}, year = {2013}, abstract = {Intra- and interspecific density dependence has profound consequences for plant population and community dynamics. In long-lived plants, however, lifetime patterns and mechanisms of density dependence are difficult to study. Here, we examine effects of intraspecific and community density on the lifetime fecundity of two long-lived shrub species from South African Fynbos: Protea repens (animal-pollinated, hermaphroditic) and Leucadendron rubrum (wind-pollinated, dioecious). Both species are serotinous, retaining seeds in cones until fire kills the mother plant. We measured lifetime fecundity as the product of cone number, proportion of cones that are not damaged by predation and seed set (fertile seeds per intact cone). Intraspecific and community densities were quantified by counting individuals of target species and all Proteaceae in small- and large-scale neighbourhoods (10 m and 50 m radius) around each focal individual. Additionally, we determined the age and size of focal individuals. We found that lifetime fecundity of the wind-pollinated L rubrum is density independent. In contrast, the lifetime fecundity of the animal-pollinated P. repens increases with large-scale intraspecific density and shows a hump-shaped relationship to large-scale community density. Community density has a hump-shaped effect on seed set (probably through partial absence of generalized pollinators at low and competition for pollinators at high densities) and negatively affects cone number per individual. For both species, plant age decreases seed set while increasing lifetime fecundity. The qualitative differences in the density dependence of lifetime fecundity may arise from differences between animal and wind pollination. In particular, interactions with generalized animal pollinators may cause community-level Allee effects with profound consequences for the future dynamics of long-lived plant populations and communities.}, language = {en} } @article{Grimshwa2006, author = {Grimshwa, Jane}, title = {Last resorts and grammaticality}, series = {Linguistics in Potsdam}, journal = {Linguistics in Potsdam}, number = {25}, issn = {1616-7392}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-32302}, pages = {33 -- 41}, year = {2006}, abstract = {A "last resort" is argued to be nothing more than a winning, i.e. grammatical form, once it is understood in terms of competition between alternative candidates. It is a theorem of OT that we find last resort effects, since it follows from the nature of competition and constraint interaction.}, language = {en} }