===firstname: Steffen ===firstname3: Thomas ===affil6: ===lastname3: Manteuffel ===email: steffen.muenzenmaier@colorado.edu ===keyword_other2: ===lastname6: ===affil5: ===lastname4: ===lastname7: ===affil7: ===postal: 1ECOT Engineering Office Tower 1111 Engineering Drive Boulder CO 80309 ===ABSTRACT: First-order system least squares (FOSLS) is a commonly used technique in a wide range of physical applications. FOSLS discretizations are straightforward to implement and offer many advantages over traditional Galerkin or saddle point formulations. Often these problems are formulated in $H(div)$ spaces and $H(div)$-conforming elements are used. These elements have lesser regularity assumptions than the commonly used $H^1$-conforming elements and are therefore believed to be more suited for singular problems arising in many applications. This talk will compare the approximation properties of the $H(div)$-conforming Raviart-Thomas and Brezzi-Douglas-Marini elements to $H^1$-conforming piecewise polynomials in a $H(div)$-setting. Furthermore a $H^1$-formulation for these problems will be used and compared to the $H(div)$-formulation. For the comparison typical Poisson/Stokes problems are examined and singular solutions will be addressed by adaptive refinement strategies. ===affil3: University of Colorado Boulder ===title: A Comparison of Finite Element Spaces for $H(div)$-Conforming First-Order System Least Squares ===affil2: University of Colorado Boulder ===lastname2: Leibs ===firstname4: ===keyword1: APP_OTHER ===workshop: no ===lastname: Muenzenmaier ===firstname5: ===keyword2: NOT_SPECIFIED ===otherauths: ===affil4: ===competition: no ===firstname7: ===firstname6: ===keyword_other1: Linear First-Order System Least Squares ===lastname5: ===affilother: ===firstname2: Christopher