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We prove that there is no algorithm that decides whether a nite relation algebra is representable. Representability of a nite relation algebra A is determined by playing a certain two player game G(A) overàtomic A-networks'. It can be shown that the second player in this game has a winning strategy if and only if A is representable. Let be a nite set of… (More)

- Robin Hirsch, Ian M. Hodkinson
- J. Symb. Log.
- 1997

We consider the problem of nding and classifying representations in algebraic logic. This is approached by letting two players build a representation using a game. Homogeneous and universal representations are characterised according to the outcome of certain games. The Lyndon conditions deening representable relation algebras (for the nite case) and a… (More)

- Robin Hirsch, Ian M. Hodkinson
- J. Symb. Log.
- 2009

A cylindric algebra atom structure is said to be strongly representable if all atomic cylindric algebras with that atom structure are representable. This is equivalent to saying that the full complex algebra of the atom structure is a representable cylindric algebra. We show that for any finite n ≥ 3, the class of all strongly representable n-dimensional… (More)

- Robin Hirsch, Ian M. Hodkinson
- J. Symb. Log.
- 1997

A boolean algebra is shown to be completely representable if and only if it is atomic, whereas it is shown that neither the class of completely representable relation algebras nor the class of completely representable cylindric algebras of any xed dimension are elementary.

- Robin Hirsch
- Artif. Intell.
- 1996

Given a representation of a relation algebra we construct relation algebras of pairs and of intervals. If the representation happens to be complete, homogeneous and fully universal then the pair and interval algebras can be constructed direct from the relation algebra. If, further, the original relation algebra is !-categorical we show that the interval… (More)

- Robin Hirsch, Ian M. Hodkinson
- Ann. Pure Appl. Logic
- 2000

We study relation algebras with n-dimensional relational bases in the sense of Maddux. Fix n with 3 ≤ n ≤ ω. Write B n for the class of non-associative algebras with an n-dimensional relational basis, and RA n for the variety generated by B n. We define a notion of relativised representation for algebras in RA n , and use it to give an explicit (hence… (More)

A relation algebra atom structure α is said to be strongly rep-resentable if all atomic relation algebras with that atom structure are rep-resentable. This is equivalent to saying that the complex algebra Cm α is a representable relation algebra. We show that the class of all strongly repre-sentable relation algebra atom structures is not closed under… (More)

- Robin Hirsch, Ian M. Hodkinson, Ágnes Kurucz
- J. Symb. Log.
- 2002

- Robin Hirsch
- Logic Journal of the IGPL
- 1995

A boolean algebra is shown to be completely representable if and only if it is atomic whereas it is shown that the class of completely representable relation algebras is not elementary.

- Robin Hirsch
- J. Symb. Log.
- 2007

There is a version of this in JSL but that version contains an error and is followed by an erratum. The erratum is encorporated into the text here. We show, for any ordinal γ ≥ 3, that the class RaCAγ is pseudo-elementary and has a recursively enumerable elementary theory. ScK denotes the class of strong subalgebras of members of the class K. atomic… (More)