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[0101] In another preferred embodiment, Polymer A may further comprise recurring units ( e) selected from units of indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, and norbornadiene, or derivatives thereof. The recurring units ( e) may be used alone or in admixture. 

[0102] Suitable monomers from which recurring units (e) are derived are exemplified below, but not limited thereto. 

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[0103] Polymer A may further comprise recurring units (f) which are derived from styrene, vinylnaphthalene, vinylan› thracene, vinylpyrene, methyleneindene, vinylpyridine, and vinylcarbazole. The recurring units (f) may be used alone or in admixture. 

[0104] In a further embodiment, Polymer A may further comprise recurring units (g) derived from a sulfonic acid onium salt having a polymerizable unsaturated bond. JP-A 2005-084365 discloses sulfonium and iodonium salts having a polymerizable unsaturated bond capable of generating a sulfonic acid. JP-A 2006-178317 discloses a sulfonium salt having sulfonic acid directly attached to the main chain. 

[0105] The preferred recurring units (g) are recurring units having the following formulae (gl), (g2) and (g3). These units are simply referred to as recurring units (gl), (g2) and (g3), which may be used alone or in combination of two or more types. 

[0106] In formulae (gl) to (g3), RA is each independently hydrogen or methyl. Z 1 is a single bond, phenylene group, ---O-Z 12 -, or -C(=0)-Z$^{11}$-Z 12 -, wherein Z 11 is ---0- or -NH-, and Z$^{12 }$is a C$_{1}$-C$_{6 }$ alkanediyl, C$_{2}$ -C$_{6 }$ alkenediyl or phenylene group, which may contain a carbo› nyl, ester bond, ether bond or hydroxyl moiety. Z $^{2 }$is a single bond, -Z$^{21}$----C(=0)-0-, -Z $^{21}$---0- or -Z$^{21}$-0- C(=0)-, wherein Z $^{21 }$is a C$_{1 }$-C$_{12 }$alkanediyl group which may contain a carbonyl moiety, ester bond or ether bond. Z 3 is a single bond, methylene, ethylene, phenylene or fluori- 

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