On <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-2.890499pt" id="M1" height="18.3634pt" version="1.1" viewBox="-0.0657574 -15.4729 141.734 18.3634" width="141.734pt"><g transform="matrix(.017,0,0,-0.017,0,0)"><path id="g50-41" d="M309 -142C211 -61 151 99 151 271S210 601 309 683L288 710C141 611 75 451 75 272V271C75 90 141 -72 288 -169L309 -142Z"/></g><g transform="matrix(.017,0,0,-0.017,6.143,0)"><path id="g50-108" d="M485 418C485 434 469 451 441 451C389 451 312 387 255 335C221 304 194 278 159 242H157L259 678C264 698 264 710 255 710C242 710 183 681 96 673L90 643L128 642C165 641 171 640 162 602L24 -5L31 -12C51 -4 81 4 110 9L145 181C154 195 180 220 205 242C233 170 263 106 291 53C318 1 335 -12 360 -12C383 -12 425 0 483 82L463 105C437 79 411 57 400 57C388 57 378 68 355 110C329 156 288 244 268 298C299 333 355 376 405 376C426 376 440 373 448 368C453 365 465 368 468 373C477 386 485 405 485 418Z"/></g><g transform="matrix(.017,0,0,-0.017,14.878,0)"><path id="g50-45" d="M98 134C72 134 46 117 46 90C46 73 55 65 60 64C95 55 124 32 124 -4C124 -42 95 -68 44 -89L57 -123C122 -104 194 -60 194 22C194 94 136 134 98 134Z"/></g><g transform="matrix(.017,0,0,-0.017,21.857,0)"><use xlink:href="#g50-108"/></g><g transform="matrix(.017,0,0,-0.017,30.814,0)"><path id="g50-111" d="M504 89L488 119C453 85 428 69 416 69C408 69 405 75 412 102L462 304C492 438 460 451 436 451S388 441 356 423C311 397 229 336 170 256H168L189 340C208 418 200 451 177 451C144 451 82 413 24 352L40 322C65 345 98 369 108 369C114 369 119 363 112 335L28 -3L36 -12C54 -3 83 4 112 10C125 73 138 122 153 174C205 258 328 382 376 382C395 382 399 369 384 305L330 93C312 25 323 -12 351 -12C378 -12 439 21 504 89Z"/></g><g transform="matrix(.017,0,0,-0.017,43.482,0)"><path id="g54-33" d="M556 236V289H56V236H556Z"/></g><g transform="matrix(.017,0,0,-0.017,57.848,0)"><use xlink:href="#g50-108"/></g><g transform="matrix(.012,0,0,-0.012,66.582,-7.751)"><path id="g50-51" d="M414 144C384 79 371 75 317 75H135L276 221C367 316 408 376 408 465C408 570 327 635 237 635C179 635 131 609 100 575L42 494L67 471C94 510 138 565 205 565C277 565 321 517 321 435C321 348 258 270 195 195C146 137 88 81 33 26V0H411C423 44 433 88 446 135L414 144Z"/></g><g transform="matrix(.017,0,0,-0.017,76.993,0)"><use xlink:href="#g54-33"/></g><g transform="matrix(.017,0,0,-0.017,91.359,0)"><use xlink:href="#g50-51"/></g><g transform="matrix(.017,0,0,-0.017,99.715,0)"><use xlink:href="#g50-108"/></g><g transform="matrix(.017,0,0,-0.017,112.332,0)"><use xlink:href="#g54-33"/></g><g transform="matrix(.017,0,0,-0.017,126.698,0)"><path id="g50-50" d="M389 0V32C297 38 291 46 291 118V635C234 613 175 595 109 583V556L161 554C203 552 207 547 207 497V118C207 46 201 38 110 32V0H389Z"/></g><g transform="matrix(.017,0,0,-0.017,135.054,0)"><path id="g50-42" d="M283 271C283 451 220 610 70 710L48 683C146 603 207 443 207 271S149 -59 48 -142L70 -169C220 -67 283 90 283 271Z"/></g></svg>-Choosability of <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-0.2724395pt" id="M2" height="8.19251pt" version="1.1" viewBox="-0.0657574 -7.92007 8.95038 8.19251" width="8.95038pt"><g transform="matrix(.017,0,0,-0.017,0,0)"><use xlink:href="#g50-111"/></g></svg>-Vertex Graphs

<div>The 7-vertex graph with chromatic number <svg height="8.38559pt" id="M316" style="vertical-align:-0.04980946pt" version="1.1" viewbox="-0.0498162 -8.33578 6.45437 8.38559" width="6.45437pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M462 177V227H365V632H320C217 496 116 350 21 208V177H284V109C284 43 280 38 190 31V0H451V31C369 38 365 43 365 108V177H462ZM284 227H88C155 336 218 430 282 519H284V227Z" id="g50-53"></path><glyph.data ascent="3443" descent="-2856" horiz-adv-x="487" vert-adv-y="487"></glyph.data></g></svg> and having no <svg height="11.6478pt" id="M317" style="vertical-align:-3.051061pt" version="1.1" viewbox="-0.0498162 -8.59674 14.402 11.6478" width="14.402pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M771 650H519L511 619L537 615C578 610 579 600 539 564C444 476 379 428 336 396C312 378 281 357 252 347L283 514C300 605 304 610 388 619L395 650H134L127 619C212 610 216 605 199 514L130 140C112 41 103 38 28 31L18 0H281L288 31C201 40 198 41 216 140L246 311C274 328 289 324 315 284C393 167 458 86 528 0H686L695 31C635 37 612 45 570 97C521 156 420 285 361 367L596 549C663 601 684 609 764 620L771 650Z" id="g50-76"></path><glyph.data ascent="3443" descent="-2856" horiz-adv-x="783" vert-adv-y="783"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,9.321,3.001)"><path d="M462 177V227H365V632H320C217 496 116 350 21 208V177H284V109C284 43 280 38 190 31V0H451V31C369 38 365 43 365 108V177H462ZM284 227H88C155 336 218 430 282 519H284V227Z" id="g50-53"></path><glyph.data ascent="3443" descent="-2856" horiz-adv-x="487" vert-adv-y="487"></glyph.data></g></svg> and <svg height="11.9661pt" id="M318" style="vertical-align:-3.16057pt" version="1.1" viewbox="-0.0498162 -8.80553 41.9706 11.9661" width="41.9706pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M690 629C653 643 577 667 483 667C225 667 24 528 24 292C24 92 174 -17 367 -17C448 -17 534 1 570 10C592 34 642 131 658 174C648 180 639 186 629 192C562 89 499 21 382 21C223 21 130 138 130 298C130 467 255 627 462 627C582 627 643 589 650 462L686 466C689 517 688 580 690 629Z" id="g50-68"></path><glyph.data ascent="3443" descent="-2856" horiz-adv-x="714" vert-adv-y="714"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,8.736,3.001)"><path d="M158 548H390L417 615L410 623H122L83 318C105 326 143 337 185 337C296 337 350 275 350 188C350 116 308 42 225 42C164 42 122 74 100 93C90 101 82 99 72 92C60 82 51 68 50 59C48 46 52 38 66 24C82 9 125 -12 172 -12C225 -11 292 15 346 59C408 108 437 166 437 226C437 309 371 397 242 397C214 397 170 382 133 369L158 548Z" id="g50-54"></path><glyph.data ascent="3443" descent="-2856" horiz-adv-x="487" vert-adv-y="487"></glyph.data></g><g transform="matrix(.013,0,0,-0.013,16.623,0)"><path d="M598 555H532L307 72H305L80 555H14L273 0H339L598 555Z" id="g54-64"></path><glyph.data ascent="3443" descent="-2856" horiz-adv-x="611" vert-adv-y="611"></glyph.data></g><g transform="matrix(.013,0,0,-0.013,27.506,0)"><path d="M771 650H519L511 619L537 615C578 610 579 600 539 564C444 476 379 428 336 396C312 378 281 357 252 347L283 514C300 605 304 610 388 619L395 650H134L127 619C212 610 216 605 199 514L130 140C112 41 103 38 28 31L18 0H281L288 31C201 40 198 41 216 140L246 311C274 328 289 324 315 284C393 167 458 86 528 0H686L695 31C635 37 612 45 570 97C521 156 420 285 361 367L596 549C663 601 684 609 764 620L771 650Z" id="g50-76"></path><glyph.data ascent="3443" descent="-2856" horiz-adv-x="783" vert-adv-y="783"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,36.827,3.001)"><path d="M389 0V32C297 38 291 46 291 118V635C234 613 175 595 109 583V556L161 554C203 552 207 547 207 497V118C207 46 201 38 110 32V0H389Z" id="g50-50"></path><glyph.data ascent="3443" descent="-2856" horiz-adv-x="487" vert-adv-y="487"></glyph.data></g></svg>.</div>

International Journal of Mathematics and Mathematical Sciences

fig2

Figure 2

Figure 2: On <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-2.890499pt" id="M1" height="18.3634pt" version="1.1" viewBox="-0.0657574 -15.4729 141.734 18.3634" width="141.734pt"><g transform="matrix(.017,0,0,-0.017,0,0)"><path id="g50-41" d="M309 -142C211 -61 151 99 151 271S210 601 309 683L288 710C141 611 75 451 75 272V271C75 90 141 -72 288 -169L309 -142Z"/></g><g transform="matrix(.017,0,0,-0.017,6.143,0)"><path id="g50-108" d="M485 418C485 434 469 451 441 451C389 451 312 387 255 335C221 304 194 278 159 242H157L259 678C264 698 264 710 255 710C242 710 183 681 96 673L90 643L128 642C165 641 171 640 162 602L24 -5L31 -12C51 -4 81 4 110 9L145 181C154 195 180 220 205 242C233 170 263 106 291 53C318 1 335 -12 360 -12C383 -12 425 0 483 82L463 105C437 79 411 57 400 57C388 57 378 68 355 110C329 156 288 244 268 298C299 333 355 376 405 376C426 376 440 373 448 368C453 365 465 368 468 373C477 386 485 405 485 418Z"/></g><g transform="matrix(.017,0,0,-0.017,14.878,0)"><path id="g50-45" d="M98 134C72 134 46 117 46 90C46 73 55 65 60 64C95 55 124 32 124 -4C124 -42 95 -68 44 -89L57 -123C122 -104 194 -60 194 22C194 94 136 134 98 134Z"/></g><g transform="matrix(.017,0,0,-0.017,21.857,0)"><use xlink:href="#g50-108"/></g><g transform="matrix(.017,0,0,-0.017,30.814,0)"><path id="g50-111" d="M504 89L488 119C453 85 428 69 416 69C408 69 405 75 412 102L462 304C492 438 460 451 436 451S388 441 356 423C311 397 229 336 170 256H168L189 340C208 418 200 451 177 451C144 451 82 413 24 352L40 322C65 345 98 369 108 369C114 369 119 363 112 335L28 -3L36 -12C54 -3 83 4 112 10C125 73 138 122 153 174C205 258 328 382 376 382C395 382 399 369 384 305L330 93C312 25 323 -12 351 -12C378 -12 439 21 504 89Z"/></g><g transform="matrix(.017,0,0,-0.017,43.482,0)"><path id="g54-33" d="M556 236V289H56V236H556Z"/></g><g transform="matrix(.017,0,0,-0.017,57.848,0)"><use xlink:href="#g50-108"/></g><g transform="matrix(.012,0,0,-0.012,66.582,-7.751)"><path id="g50-51" d="M414 144C384 79 371 75 317 75H135L276 221C367 316 408 376 408 465C408 570 327 635 237 635C179 635 131 609 100 575L42 494L67 471C94 510 138 565 205 565C277 565 321 517 321 435C321 348 258 270 195 195C146 137 88 81 33 26V0H411C423 44 433 88 446 135L414 144Z"/></g><g transform="matrix(.017,0,0,-0.017,76.993,0)"><use xlink:href="#g54-33"/></g><g transform="matrix(.017,0,0,-0.017,91.359,0)"><use xlink:href="#g50-51"/></g><g transform="matrix(.017,0,0,-0.017,99.715,0)"><use xlink:href="#g50-108"/></g><g transform="matrix(.017,0,0,-0.017,112.332,0)"><use xlink:href="#g54-33"/></g><g transform="matrix(.017,0,0,-0.017,126.698,0)"><path id="g50-50" d="M389 0V32C297 38 291 46 291 118V635C234 613 175 595 109 583V556L161 554C203 552 207 547 207 497V118C207 46 201 38 110 32V0H389Z"/></g><g transform="matrix(.017,0,0,-0.017,135.054,0)"><path id="g50-42" d="M283 271C283 451 220 610 70 710L48 683C146 603 207 443 207 271S149 -59 48 -142L70 -169C220 -67 283 90 283 271Z"/></g></svg>-Choosability of <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-0.2724395pt" id="M2" height="8.19251pt" version="1.1" viewBox="-0.0657574 -7.92007 8.95038 8.19251" width="8.95038pt"><g transform="matrix(.017,0,0,-0.017,0,0)"><use xlink:href="#g50-111"/></g></svg>-Vertex Graphs 

International Journal of Mathematics and Mathematical Sciences

On -Choosability of -Vertex Graphs

Figure 2