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Univers."],"published-print":{"date-parts":[[2021,12]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    We study the decidability of\n                    <jats:italic>k<\/jats:italic>\n                    -provability in\n                    <jats:inline-formula>\n                      <jats:alternatives>\n                        <jats:tex-math>$$\\hbox {PA}$$<\/jats:tex-math>\n                        <mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\">\n                          <mml:mtext>PA<\/mml:mtext>\n                        <\/mml:math>\n                      <\/jats:alternatives>\n                    <\/jats:inline-formula>\n                    \u2014the relation \u2018being provable in\n                    <jats:inline-formula>\n                      <jats:alternatives>\n                        <jats:tex-math>$$\\hbox {PA}$$<\/jats:tex-math>\n                        <mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\">\n                          <mml:mtext>PA<\/mml:mtext>\n                        <\/mml:math>\n                      <\/jats:alternatives>\n                    <\/jats:inline-formula>\n                    with at most\n                    <jats:italic>k<\/jats:italic>\n                    steps\u2019\u2014and the decidability of the proof-skeleton problem\u2014the problem of deciding if a given formula has a proof that has a given skeleton (the list of axioms and rules that were used). The decidability of\n                    <jats:italic>k<\/jats:italic>\n                    -provability for the usual Hilbert-style formalisation of\n                    <jats:inline-formula>\n                      <jats:alternatives>\n                        <jats:tex-math>$$\\hbox {PA}$$<\/jats:tex-math>\n                        <mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\">\n                          <mml:mtext>PA<\/mml:mtext>\n                        <\/mml:math>\n                      <\/jats:alternatives>\n                    <\/jats:inline-formula>\n                    is still an open problem, but it is known that the proof-skeleton problem is undecidable for that theory. Using new methods, we present a characterisation of some numbers\n                    <jats:italic>k<\/jats:italic>\n                    for which\n                    <jats:italic>k<\/jats:italic>\n                    -provability is decidable, and we present a characterisation of some proof-skeletons for which one can decide whether a formula has a proof whose skeleton is the considered one. These characterisations are natural and parameterised by unification algorithms.\n                  <\/jats:p>","DOI":"10.1007\/s11787-021-00278-1","type":"journal-article","created":{"date-parts":[[2021,6,9]],"date-time":"2021-06-09T10:27:45Z","timestamp":1623234465000},"page":"477-516","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["k-Provability in $$\\hbox {PA}$$"],"prefix":"10.1007","volume":"15","author":[{"given":"Paulo Guilherme","family":"Santos","sequence":"first","affiliation":[]},{"given":"Reinhard","family":"Kahle","sequence":"additional","affiliation":[]}],"member":"297","published-online":{"date-parts":[[2021,6,9]]},"reference":[{"key":"278_CR1","first-page":"29","volume-title":"Arithmetic, Proof Theory and Computational Complexity","author":"M Baaz","year":"1993","unstructured":"Baaz, M., Pudl\u00e1k, P.: Kreisel\u2019s conjecture for L$$\\exists $$1. In: Clote, P., Kraji\u0107ek, J. 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