Jerzy Łoś
Jerzy Łoś c.1955
Born	(1920-03-22)22 March 1920 Lwów, Second Polish Republic
Died	1 June 1998(1998-06-01) (aged 78) Warsaw, Third Polish Republic
Nationality	Polish
Known for	Łoś's theorem Łoś–Tarski preservation theorem Łoś–Vaught test
Scientific career
Fields	Mathematics Logic Economics Philosophy

Jerzy Łoś (Polish pronunciation: [ˈjɛʐɨ ˈwɔɕ]^{[note 1]}; born 22 March 1920 in Lwów, Poland (now Lviv, Ukraine) – 1 June 1998 in Warsaw) was a Polish mathematician, logician, economist, and philosopher. He is especially known for his work in model theory, in particular for "Łoś's theorem", which states that any first-order formula is true in an ultraproduct if and only if it is true in "most" factors (see ultraproduct for details). In model theory he also proved many preservation theorems, but he gave significant contributions, as well, to foundations of mathematics, Abelian group theory and universal algebra. In the 60's he turned his attention to mathematical economics, focusing mainly on production processes and dynamic decision processes.

He was faculty at academies in Wrocław, Toruń, and Warsaw.

In 1996, Łoś suffered from a severe brain stroke. He was thenceforward ill until his death in 1998.

• Łoś, Jerzy (1955) Quelques remarques, théorèmes et problèmes sur les classes définissables d'algèbres. Mathematical interpretation of formal systems, pp. 98–113. North-Holland Publishing Co., Amsterdam.

• Hyperreal number – Element of a nonstandard model of the reals, which can be infinite or infinitesimal
• Łoś–Vaught test
• Łoś's theorem – Mathematical construction
• Transfer principle – Concept in model theory

• Jerzy Łoś's biography Archived 2012-07-28 at the Wayback Machine

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